Dr. Felipe Chibante
Ms. Linda Bulmer
Dept. Of Chemical Engineering
University of New Brunswick
PO Box 4400, Fredericton NB, E3B 5A3
Nov 13th, 2013
Dear Dr. Felipe Chibante & Ms.Linda Bulmer,
We have enclosed “Milestone 3” which presents a general overview of our project as well as the
results of a literature review. Background information is provided for the company Enovex as well
as the gas adsorbing materials they produce. Design and project scope are outlined providing a
frame work for future work moving forward. Results of research and comparison of three of the
most prominent MOF production processes are included as well as the results of research into the
economic viability of this project. Proceeding the literature research and process selection, a base
case design is introduced with a block flow diagram explaining the main components of the
process. Also innovative additions are implemented along with major safety and environmental
considerations.
We believe you will find this report in line with your expectations, however if you have any
questions regarding this report, please do not hesitate to contact us directly at (506) 447- 0159.
Best Regards,
Group 9.
Sarbjyot Bains (Team Leader) Omar El-kadri Yousef Aloufi
Leroy Rodrigues William Cormac Goodfellow
ChE 4225: Chemical Engineering Plant Design
Milestone 3
Production of Metal Organic Frameworks (MOFs)- Enovex
Submitted to:
Ms. Linda Bulmer
Prof. Felipe Chibante
Due Date: 11/13/2013
Submitted by:
Group 9
Abstract
The objective of the following report is to cast an overview of the process and specifications of
the projected plant for the manufacturing of Metal Organic Frameworks (MOFs) and to present
the results of a literature review designed to determine which production system is the most
desirable.
The main function of MOFs is the efficient separation of gases such as nitrogen and oxygen.
The MOFs under study are to demonstrate 2-3 times better separation in comparison to current
technologies available. General client needs include an overall design process that constitutes
environmental, economic and risk assessment studies. These assessments should enable group 9
to build a green pilot size process plant that produces an approximation of 100kg/day of plant
operation that also complies with all safety and environmental regulations. Also a description of
the feedstock and production rates are mentioned as well as anticipated purity and yield will be
discussed within.
Further research will also be performed on plant location and downstream environmental
concerns regarding possible waste water, and/or disposal of hazardous waste.
Along with all the process steps, there are many constraints to be addressed, such as economic
indicators, environmental regulations, and health and safety issues. The following report will
highlight several key points that outline a responsible and sustainable operation.
Research was done into the economic viability of this project and the findings were encouraging.
There is significant market demand for materials of this type. Though a scale up of the process is
unproven, which could be seen as a liability, it is this same characteristic which gives this project
the potential for tremendous opportunity. Maximum potential profit was determined by
comparing the product market value and the costs of the precursor chemicals.
The results of an extensive literature review are presented detailing comparisons made between
three of the most prominent MOF production methods. The 3 processes examined were the
Electrochemical, Microwave Assisted and Solvothermal. Advantages and disadvantages of these
production methods were detailed and careful consideration was given in order to select the
process that will most suit Enovex’s needs. It was determined that the solvothermol process had
significant overall advantage when compared to the other methods.
Further proceeding the literature review and process selection, a base case design is introduced
demonstrating the main components of the design via a block flow diagram. Also explanation in
detail is presented for each section of the proposed BFD. Also innovative additions are
suggested, such as an overall control system that monitors and controls the process along with
recycling streams that recycle the expensive solvents needed for the process.
1
Contents 1. Project Definition ...................................................................................................................................... 3
1.1 Introduction ........................................................................................................................................ 3
1.2 Design Scope ....................................................................................................................................... 4
1.2.1 General Client Needs ................................................................................................................... 4
1.2.2 Feedstock ..................................................................................................................................... 6
1.2.3 Plant Location and Environment .................................................................................................. 7
1.2.4 Decision Criteria/ Constraints ...................................................................................................... 9
1.3 Project Scheduling ............................................................................................................................ 11
2.0 Literature review ................................................................................................................................... 12
2.1 Overview of Product Markets ........................................................................................................... 12
2.1.1 Product End Uses ....................................................................................................................... 12
2.1.2 Product Specifications ................................................................................................................ 14
2.1.3 Product Pricing ........................................................................................................................... 15
2.1.4 Product Supply and Existing Producers ..................................................................................... 15
2.1.5 Product Demand ........................................................................................................................ 16
2.2 Assessment of Alternative Process Technologies ......................................................................... 16
2.2.1 Electrochemical Synthesis Process ............................................................................................ 16
2.2.2 Microwave Assisted Synthesis ............................................................................................ 19
1.2.3 Solvo/Hydro Thermal Synthesis Process ............................................................................. 22
2.5 Competitive Cost Considerations ...................................................................................................... 24
2.6 Recommended Process Technologies ............................................................................................... 25
2.7 Maximum Potential Profit ................................................................................................................. 29
3.0 Base Case Design ............................................................................................................................. 30
3.1 Pre-activation process ................................................................................................................. 32
3.1.1 Reactor process and chemistry .................................................................................................. 32
3.1.2 Filtration ..................................................................................................................................... 33
3.1.3 Drying ......................................................................................................................................... 33
3.1.4 Soaking ....................................................................................................................................... 33
3.1.5 Filtration ..................................................................................................................................... 34
3.1.6 Recycle Streams ......................................................................................................................... 34
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3.2 Activation Process ............................................................................................................................. 34
3.3 Innovation ......................................................................................................................................... 35
3.3.1 Process control and data analysis .............................................................................................. 35
3.3.2 Solvent Recycling ....................................................................................................................... 36
3.4 Health, Safety and Environmental Considerations ........................................................................... 37
3.4.1 Health and safety ....................................................................................................................... 37
3.4.2 Environmental ............................................................................................................................ 38
4.0 References ............................................................................................................................................ 39
5.0 Appendix ............................................................................................................................................... 41
Tables and Figures
Table 1- Project Schedule. .......................................................................................................................... 12
Table 2:BASF Grades. ................................................................................................................................ 14
Table 3: Product Pricing ............................................................................................................................. 15
Table 4: Electrochemical Synthesis, advantages and disadvantages summary table. ............................... 19
Table 5: Microwave Assisted Synthesis, advantages and disadvantages summary table. ......................... 21
Table 6: Solvothermal Synthesis Process, advantages and disadvantages................................................. 24
Table 7: Pros and Cons based comparison. ................................................................................................ 26
Table 8: Process Selection Matrix based on risk and value assessment according to aspect weight on
process. ....................................................................................................................................................... 27
Table 9: Raw Material Prices. ...................................................................................................................... 29
Table 10: Process aspect grading points. .................................................................................................... 41
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1. Project Definition
1.1 Introduction
Enovex is a leading technology startup company based in Atlantic Canada specializing in advanced
materials for improved separation capacities for portable and industrial O2/N2 production. Refined
O2 and N2 are both high demand products used for many purposes both industrially and
commercially. The oxygen for example is supplied to hospitals, steel and metal processing
industries among others. One of the largest users of refined nitrogen are the food industries whose
main uses are for freezing applications. There are many other uses of these products making this a
multimillion dollar industry.
Enovex has designed a unique porous material, which separates 2 to 3 times as much gas as the
existing materials available and result in a 50% drop in energy usage in the production of industrial
nitrogen. This material has the potential to reduce gas plant size by up to 66%. These high
performance materials called Metal Organic Frameworks or MOFs are a new class of porous
polymer materials which combine metals with organic ligands. They are highly tunable and
favorable for industrial gas processes (Walton, 2013).
The existing technology for non-cryogenic N2 production , carbon molecular sieves (CMS), are
inefficient and have a number of operational problems including; slow mass transfer due to kinetic
based separation, long mass transfer zones, low product recovery, limited volumetric uptake and
low material tune-ability. To address these problems Enovex has invented a metal organic
framework or MOF which exhibits equilibrium O2 selectivity, high O2 capacity and a linear
isothermal shape. Other desirable attributes include; functionalized pores for high O2 selectivity,
4
a mix of meso and micro pores providing favorable kinetics and material also provides reversible
O2 adsorption (Walton, 2013).
Enovex plans to scale up the existing lab scale production processes to a commercialized pilot
enabling the contracted manufacture of the MOF material. Distribution will be accomplished by
using the supply channels of a large gas company. To date the Enovex team has raised $2.5M in
cash and $2M in capital equipment investments as well as hired multiple leading material scientists
including a consultant who is a premier scientists in the field. Enovex’s assets include a laboratory
in India with advanced equipment and have also built a PSA lab in Canada for commercial testing.
It is our teams’ intention to fulfill the client’s expressed need to advance the conceptualization,
design and specification of a MOF production facility capable of producing kilogram sized batches
of Enovex’s product (Walton, 2013).
1.2 Design Scope
The following section will be discussing general client specifications that outline the scope of design
project. Also some of the out of scope aspects are mentioned. Further discussion includes health and
safety aspects that define the decision criteria for process selection.
1.2.1 General Client Needs
Enovex has requested group 9 to design a commercialized sized pilot plant for the production of
MOF’s that have the function of separating oxygen gas from nitrogen gas via absorption. Currently
there is no existing plant for the projected design, hence the client requirements include every
5
single aspect of the process design from utilities, feedstock used, to final product, pelletizing and
packaging (Walton, 2013).
The process design requirements include:
The selection of plant location based on financial aspects determined by comparing the
proximity of the plant to both the supplier of the raw materials and the buyer of the product
(Walton, 2013).
The building of the plant with all the process components from reactors, boilers, stream
lines and utility feeds to the pelletizing, packaging and storage of the product (Walton,
2013).
Abiding by all safety and design regulation set by provincial laws that govern such
processes.
Building and performing tasks based on green plant design strategies. Further safety
systems such as fire suppression systems and other non-process related designs will be
contracted to firms specialized in these fields (Walton, 2013).
Continuous monitoring of the process and input is also required. Certain indicators need
to be collected during the process to ensure input and process integrity.
An overall economic assessment for the feasibility of the plant and profitability of the
product is also a task that group 9 is required to perform with special attention for payback
period and other financial aspects of the design.
A deadline for the plant design limited at a maximum range of three years must be met
(Walton, 2013).
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1.2.1.1 Beyond Scope Limits
Optimization of the formulation.
Competitive-end of the final product.
1.2.2 Feedstock
The feedstock is a set of raw materials required for the entire process of manufacturing MOFs.
The main industrial function for MOFs is to replace existing technologies for non-cryogenic N2
production such as carbon molecular sieves (CMS). The raw materials to be processed in the plant
include metal salts (Zinc Nitrate), solvents/co-solvents (N,N-dimethylformamide), ligands/co-
ligands (Terephthalic acid) along with supplementary additives. The projected plant size is limited
to a small pilot plant that will produce approximately 100kg/day. The production rate can be
estimated conservatively to project feedstock rate in the case of having a specific production rate
requirement from Enovex. In this project case the production rate is a variable in determining the
optimal feed for the optimal product. Hence precise feedstock volumes will be determined based
on experimental trials that would find the optimal feed rates for the highest quality and yield of
product. Based on client requirements, the anticipated purity should be 95% or greater and will be
tested using a powder x-ray diffraction device. Further tests can be performed via FTIR and
physisorption to determine optimal surface area and pore volume. The process will start with an
approximation for feedstock quantities and then results of experimental trials will determine
optimal feedstock rates. Tests that are required to determine the pore size and optimal structure are
beyond the process scope, and are the responsibility of Enovex (Walton, 2013).
MOF’s can be generally described as a class of porous polymeric materials, consisting of metal
ions linked together by organic bridging ligands. The raw materials used are not the actual
7
materials to be processed, where Enovex will keep this information confidential for patenting
purposes. Group 9 will be using analogous materials that will allow proper design of the process
(Walton, 2013).
1.2.3 Plant Location and Environment
The following section will discuss the variables that affect plant location as well as
environmental concerns that relate to the best location.
1.2.3.1 Plant Location Selection
The three locations that are currently being considered for the plant are:
Saint John, NB Canada, where it is in proximity to the client’s headquarters and port of
Saint John. Land costs are low but production costs very high.
India, where it is in proximity to Enovex’s Research and Development Centre and has
numerous ports for quick shipping of the product.
Europe, where it is in close proximity to most of the major clients of Enovex. It is
centrally located on the map and this makes it the best location for transportation
throughout the world.
A recommendation for plant site will be based on the following considerations:
Product distribution: Site should be in proximity to clients (air separation plants).
Feedstock availability: Site should be in proximity to required feedstock.
Relevant climatic conditions: Site should have controllable humidity as the end product is
sensitive to humidity. Site meteorology and weather conditions should be assessed.
8
Property costs: The property prices and property taxes should be low to match Enovex’s
budget.
Labor Costs and Expertise Availability: Skilled labor should be available at affordable
cost. Direct labor costs include wages plus payroll, benefits and related taxes.
Regulatory environment: The local, state and federal laws and regulations should be
taken into consideration for site selection.
Geotechnical conditions: Borings must be obtained early in the process to attain the cost
and schedule implications foundation designs, structural fill, soil compaction, surcharging
and piling.
Availability of Public Sector Funding: Grants will help in reducing land costs and taxes.
Potential for expansion: The site should be large enough to expand the pilot plant into a
commercial plant.
Exact location and specific dimensions will be provided at a later date.
1.2.3.2 Environmental Concerns
A critical concern in the design of a chemical plant is its impact on the environment.
Potential concerns include:
Disposal of hazardous waste: The hazardous waste would be the unconsumed reagents in the
effluent. The non-recyclable waste material will go through an incinerator and the residue will
be landfilled. Moreover, under the reaction conditions used there is no appreciable
decomposition into other materials. Rejected finished product is also a non-recyclable source of
waste to be addressed.
9
Proper operating and disposal procedures will be formed to prevent potential impacts on the
environment. A list of critical environmental permits and plans would be developed for the
chosen location by an environmental consulting company. Proper level of safety would be
provided to prevent exposure to hazardous conditions.
1.2.4 Decision Criteria/ Constraints
Flushing out and evaluating a number of process constraints will prove to be of great importance
in the process of decision-making and selecting the process design and its components. Most of
these constraints directly affect the quality and performance of the final product. Constraints
include economic feasibility, environmental risks, safety risks, technological feasibility and
regulatory issues.
1.2.4.1 Environmental aspects
Since this particular process deals with chemicals that are harmful to the environment or/and
human life, a number of safety measures will be necessary. Most of the raw materials that will be
used in the process processes flammable properties and produce hazardous vapors, therefore
measures will be needed to be taken in order to prevent any harmful effects to the environment.
Another aspect that needs to be taken into consideration is the handling of the hazardous waste.
These constrains will play an important role in finalizing the location of the plant (Wilkins, 2012).
1.2.4.2 Health and Safety
A number of measures need to be taken in order to minimize health hazards. This particular product
deals with toxic vapors, therefore the employees will need to follow proper safety protocols in
order to ensure their safety. Also safety measures will be needed to be taken in order to prevent
10
the escape of these harmful vapors to the surroundings. Some of the feeds (raw materials) processes
highly flammable properties, therefore safety precautions will be needed in order to prevent any
associated injury or damage (Walton, 2013). The raw materials and products of this process
haven’t been tested on a pilot scale, therefore more lab scale testing needs to be conducted to
ensure smooth pilot scale operation.
1.2.4.3 Economic Feasibility
A critical constraint that most industries face is financial. Since this plant is dealing with a new
product a fixed budget has not yet been set by the client, but a predicted healthy cash flow will be
essential to maintain investor interest and sustain long term operational viability.
1.2.4.4 Technological Risks
Since this project is currently at laboratory stage, proper equipment selection will be of primary
importance. One of the key criteria for this project is the purity and yield of the product, therefore
if economically feasible, control systems can be implemented throughout the process to ensure
optimum product results. An important aspect with regards to the selection of the technologies is
the cost of the equipment and facilities.
1.2.4.5 Production Reliability
An important operational constraint is a reliable power supply. The design should include some
form of power redundancy in order to ensure smooth operation of the plant.
11
1.2.4.6 Legal Regulations
Since this particular plant deals with hazardous materials it is essential to abide by associated codes
and regulations in with its hosted location. The codes will focus on all the minor and major aspects
of the plant design, these include the handling of waste and quality of air. These codes will ensure
the safety of the workforce and surrounding areas. This factor could play an important role in
selecting the location for the plant.
1.3 Project Scheduling
Figure 1- Gantt Chart
12
The following table lists specific dates for project milestones and deadlines.
Table 1- Project Schedule.
2.0 Literature review
The following section will discuss product end uses, and the market available for MOF-5 being
produced. Further research and discussion casts an overview of the selection process and
potential profit for the MOF production using the solvothermal process.
2.1 Overview of Product Markets
2.1.1 Product End Uses
North America’s developing interest in environmentally conscious processes and products, has
stimulated a great deal of interest in the use of MOFs in non-cryogenic nitrogen production.
Scientists at Enovex are trying to develop highly porous and tunable MOFs with favorable
characteristics for industrial gas separation. Their huge surface area and pore volume makes them
extremely useful for gas sequestration and as a catalyst.
MOFs are an extremely useful product with multiple uses:
13
Hydrogen Storage: Hydrogen is a clean energy carrier and potential replacement for
petroleum products. Hydrogen storage is a critical enabling technology for the acceptance
of hydrogen powered vehicles and MOFs play a great role in storing sufficient hydrogen
at low temperatures and pressures (Yaghi, O'Keeffe, Cordova, & Furukawa, 2013).
CO2 sequestration: MOFs show substantial CO2 adsorption capacities at low and high
pressures.
Catalysis: MOFs have a huge potential in numerous catalyst applications. Their high
surface area, tunable porosity, diversity in metal and functional groups makes them highly
suitable as catalysts (Seda & Seda, 2011).
Semiconductors: It has been proven through theoretical calculations that MOFs show
properties of semiconductors and insulators with band gaps ranging between 1.0 eV and
5.5 eV.
Air Separation: MOFs have high selectivity for oxygen and the adsorption process is
completely reversible.
Drug Delivery Vehicles: MOFs can be regarded as optimal drug delivery materials due to
the possibility of adjusting their framework’s functional groups and tuning of their pore
size. (Seda & Seda, 2011)
Potential Imaging Agents: A recent study demonstrated the potential use of nanoscale
MOFs as multimodal imaging probes designed by incorporation of suitable metal ions and
organic moieties using a microemulsion-based approach (Seda & Seda, 2011).
MOFs for Sensing: MOFs having luminescent properties together with size/shape selective
sorption properties can be considered as potential sensing devices
14
2.1.2 Product Specifications
Currently, BASF is the only commercial producer of MOFs. The various grades available at BASF are
shown below: (Aldrich, 2013).
Table 2:BASF Grades.
BASOLITE A100 (C8H5AlO5) Hydrophilic Aluminum MOF
BET surface area 1100-1500 m2/g
Reactivation at 200oC
BASOLITE C300(C18H6Cu3O12) Hydrophilic Copper MOF
BET surface area 1100-2100 m2/g
Reactivation at 200oC
BASOLITE Z1200(C8H12N4Zn) Organophilic Zinc, ZIF, Zeolitic
Framework
BET surface area 1300-1800 m2/g
Reactivation at 100oC
The product specification of the MOF produced by Enovex is:
Product Name: MOF-5 or IRMOF (Isoreticular Metal Organic Framework)-1
Formula: Zn4O(C8H4O4)3
Appearance(Color): Orange
Appearance (Form): Micro crystals
Infrared spectrum: Conforms to Structure
Purity (GC) > 99.5 %
15
2.1.3 Product Pricing
Price of MOFs is directly proportional to their surface area per gram and purity. The prices shown
below are for lab samples and would vary for commercial applications (Aldrich, 2013).
Table 3: Product Pricing
Product Price(in $ per 100 g
of MOF)
BASOLITE A100 1295.00
BASOLITE C300 1815.00
BASOLITE Z1200 1295.00
MOF-5
50.00
From literature, it is found that MOFs have higher value in biomedical applications than in air
separation applications.
2.1.4 Product Supply and Existing Producers
The MOFs sold by Sigma-Aldrich are manufactured in a BASF pilot plant in Ludwigshafen,
Germany, in 100-kg-per-day batches. Only a portion of the plant's output is sold via Sigma-Aldrich
and that BASF uses most of the material internally for various R&D projects. It is seen that
industrial scientists in many companies are investigating framework compounds for use in
purification, storage, and transportation of gases, among other applications. (Jacoby, 2008)
The existing producers of MOFs include:
1. BASF: It is the only commercial producer of MOFs.
2. Sigma Aldrich: Supplier of customized MOFs on a lab scale.
3. Unknown Suppliers on Chemical Trading Websites: Supply reagent grade MOFs up to
five grams per day.
16
2.1.5 Product Demand
MOFs are currently at Research and Development stage and therefore most of the demand is
coming from labs across the world for finding new applications of MOFs.
However, in the near future, predicted demand for MOFs is in the following sectors:
Automobile: For large scale hydrogen and methane storage.
Gas Separation: Separating oxygen and nitrogen from the air.
Reactors: As a catalyst with large surface area.
2.2 Assessment of Alternative Process Technologies
The following sections will discuss the main disadvantages and advantages of the three most
favorable processes in the industry; electrochemical synthesis, microwave assisted synthesis and
solvothermal synthesis.
2.2.1 Electrochemical Synthesis Process
Electrochemical synthesis is the synthesis of chemical compounds in an electrochemical cell.
During the electrochemical synthesis process metal ions are continuously supplied through the
anodic dissolution. It is an effective and versatile means of producing MOF’s. The figure below
provides a basic overview of an electrochemical synthesis process for the production of MOF’s.
17
Figure 2: Electrochemical Synthesis of Metal Organic Framework.
2.2.1.1 Advantages
Some of the major advantages of an electrochemical synthesis process that makes it applicable in
an industry are:
Short Reaction Time: The reaction time for the implementation of an electrochemical
synthesis process is much faster than the conventional methods of synthesis. It is also
possible to have the system set in a continuous process.
Controllability of the size of the crystals: The size of the crystals can be controlled by the
manipulation of the voltage and concentration of metal ions. This can prove to be a key
feature as the specifications of the product can be altered to fit the needs of the client.
Elimination of the separation process of the anions from the synthesis solution and total
utilization of the linker: The process uses metal ions instead of metal salts. This eliminates
the reaction of the metal salts with the dissolved linker molecules that are present in the
reaction medium. Therefore total utilization of the linker can be accomplished. Also there
18
is no need to separate the anions from the synthesis solution, prior to the recycling of the
solvent.
2.2.1.2 Disadvantages
The major disadvantages of an electrochemical synthesis process that makes it unsuitable for an
industrial application are:
Lower overall efficiency of the product: During the reaction some of the material that was
used in the initial stage of the electrochemical process may get trapped inside the pores,
resulting in pore blockage. This will decrease the overall efficiency of the product in terms
of adsorption.
Variation in the final product: Certain areas of the material that are electrically connected,
are the only areas that are subject to the growth. Therefore there is less uniformity in the
final product.
Cost-intensive: An electrochemical process is an expensive process to conduct. Also the
electrodes that are used during the course of the experiment, need to be changed
continuously. This will increase the overall operating cost of the plant.
Scalability of process: The electrochemical process for the manufacturing of MOF’s has
not yet been tested in an industrial application. Therefore the process may prove to be
unreliable.
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Table 4: Electrochemical Synthesis, advantages and disadvantages summary table.
Advantages Disadvantages
Short Reaction Time Lower overall efficiency of the product
Controllability of the size of the crystals Variation in the final product
Elimination of the separation process of the
anions from the synthesis solution and total
utilization of the linker
Cost-intensive
Unreliability of process
2.2.2 Microwave Assisted Synthesis
2.2.2.1 Overview of process technology
In Microwave-Assisted Synthesis, an appropriate solvent which contains a substrate mixture is
transferred to a vessel. After transferring the solvent to a vessel, the vessel is sealed and placed in
the microwave oven. At the set temperature, the microwave oven will heat the content for the
appropriate time. The permanent dipole moment of the molecule in the synthesis medium is
coupled with an applied oscillating electric field inducing molecular rotations hence resulting in
rapid heating of the liquid phase (Kerner, Palchik, & Gedanken, 2001).
Figure 3: Microwave-assisted solvothermal synthesis of MOF structures (Kerner, Palchik, & Gedanken, 2001).
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2.2.2.2 Process Chemistry
For the synthesis of microcrystals of Isoreticular Metal Organic Framework (IRMOF-1)
dissolution of a mixture of an appropriate spacing ligand and a metal precursor in N,N-
diethylformamide (DEF) solvent. In order to create a homogenous seeding environment, the
mixture is continuously stirred for about 15 minutes to get a clear solution (Jhung, et al., 2005).
H2BDC + Zn(NO3)2•4H2O Zn4O(BDC)3•(DEF)7
In a typical synthesis, an exact amount of benzenedicarboxylic acid (H2BDC) (0.033 g, 0.20 mmol)
and Zn(NO3)24H2O (0.156 g, 0.60 mmol) is dissolved in 12 mL N,N-diethylformamide (DEF)
resulting in a clear solution. The solution is heated in a microwave synthesizer for 25 seconds.
After the microwave treatment a yellow suspension is formed. The product is centrifuged and
redispersed in DEF by sonicating several times before analysis. The resulting suspended particles
of IRMOF-1 are found to be micro-sized cubic crystals with an average size of 4± μ m (Kang,
Park, & Wha-Seung, 1999).
2.2.2.3 Advantages
The advantages include:
Fast crystallization and phase selectivity: microwave assisted synthesis has advantages in
effectively saving reaction time, hastening the crystallization process, and producing
phase-pure products of MOF materials in high yield and large scale.
Narrow particle size distribution and facile morphology control.
Controllable process: commercial microwave equipment provides adjustable power
outputs and has a fiber optic temperature controller and pressure controller.
21
The ability to produce new products: the growth process is not depending on nucleation
on the walls or dust particles so it allows new types of MOFs to be discovered (Kang,
Park, & Wha-Seung, 1999) (Jhung, Chang, Hwang, & Park, 2003).
2.2.2.4 Disadvantages
The disadvantages include:
Limited reproducibility: hindering reproducibility is a main issue to be considered in
microwave heating. The reaction conditions can by varied by controlling the temperature,
reaction time, and irradiation power. Different instruments are unable to give the same
conditions, ultimately hindering reproducibility (Kang, Park, & Wha-Seung, 1999).
Dangerous process: microwave heating is dangerous. Heating a closed vessel containing
volatile solvents and nitrates can cause an explosion. It creates hot spots that can accelerate
the explosion. In particular the pressure in a vessel containing a volatile solvent can be
much higher than with conventional synthesis (Jhung, Chang, Hwang, & Park, 2003).
Not yet commercialized: High manufacturing risks and no commercial scale process yet
seen light.
Table 5: Microwave Assisted Synthesis, advantages and disadvantages summary table.
Advantages Disadvantages
Fast Crystallization Limited reproducibility
Narrow particle size distribution Dangerous process
Controllable process Not commercialized yet
Producing new products
22
1.2.3 Solvo/Hydro Thermal Synthesis Process
In a sealed vessel, such as a bomb or autoclave, solvents can be brought to temperatures well above
their boiling points by the increase in autogenously pressures resulting from heating. Performing
a chemical reaction under such conditions is referred to as solvothermal processing or, in the case
of water as solvent, hydrothermal processing (Yu, 2005). Solvents other than water can provide
milder reaction conditions with lower energy requirements (Yang, 2006).
Figure 4: A Graphical Representation of a Typical Autoclave.
MOFs, until now, have generally been prepared by either hydrothermal or solvothermal synthesis
methods by electric heating in small scales. Solvothermal methods have a benefit of the sol-gel
methods as well as a benefit of the hydrothermal methods. (Oliveira, Schnitzler, & Zarbin, 2003)
Benefits are precise control over the size, shape distribution, and crystallinity of the nanostructures
produced. Also, reaction temperature, reaction time, solvent type, metal salt and organic ligand
precursors can all be varied in order to achieve the desired MOF specifications.
Stainless steel autoclave (1) Precursor solution (2) Teflon liner (3) Stainless steel lid (4) Spring (5)
23
2.2.3.1 Advantages
The advantages include:
Proven technology in small scale: many different MOF types using different precursors
and under different reaction conditions have been theorized and thoroughly tested in the
lab.
Leading technology: Opportunity to be a technological leader in this area.
High Demand: Currently a demand for such a material that is currently not being met
(Walton, 2013).
Low energy consumption: the solvothermal method in particular requires low heat input to
satisfy reaction temperature requirements (Yang, 2006).
Milder reaction conditions: The solvothermal method generally requires milder reaction
conditions, than hydrothermal, which allow the use of less costly equipment and lower
capital cost (Yang, 2006).
Precise specification control: MOF pore volume and structure can be more precisely
controlled to obtain material best suited to the application it was designed for.
2.2.3.2 Disadvantages
The disadvantages include:
Long reaction times: Reactions can take from hours to days to complete (Kang, Park, &
Wha-Seung, 1999).
Expensive equipment: Reaction pressures above atmospheric and nonstandard equipment
increase capital costs.
24
Unproven in large scale: Most MOF types have not been produced in more than gram
scale quantities per batch (Kim, Hye-Young Cho, & Wha-Seung Ahn, 2012).
Table 6: Solvothermal Synthesis Process, advantages and disadvantages.
Advantages Disadvantages
Proven technology Long Reaction Times
Leading technology Expensive equipment
High Demand Unproven in large scale
Milder reaction conditions
Precise specification control
2.5 Competitive Cost Considerations
The current process for MOFs production is in the R&D stage. The only company that has
commercialized (pilot size) the manufacturing of MOFs is BASF which generates approximately
$1.5 million per day for producing 100 kg of MOFs.
There are many factors to consider upon assessing the overall production costs, such as:
Raw material costs
Labor rates based on location of plant (country)
Operational and maintenance costs
Utilities
Packaging
Equipment costs
25
2.6 Recommended Process Technologies
MOF’s optimization is highly dependent on process tuning and monitoring as well as the
assessment of the flexibility and controllability of the process along with economic factors,
environmental concerns and safety issues. An assessment for the top three processes available for
MOF’s manufacturing has been conducted in section 2.4. The three processes that were found to
be the most commonly used processes for MOF’s production are the electrochemical synthesis
process, the micro-wave assisted synthesis process and the solvothermal synthesis process.
In the following three tables the selection process is conducted based on three criteria:
Pros and Cons based selection.
Value and risk evaluation method.
Grade point average for processes (see appendix).
A risk and value diagram also demonstrates the position of each process in terms of risk and value.
The most favorable placement is for the upper right quadrant which designates lower risk and
higher value.
26
Table 7: Pros and Cons based comparison.
Process (Row)
Aspect (column)
Electrochemical Synthesis Micro-wave assisted
synthesis
Solvothermal synthesis
Reaction time Faster than other
conventional methods
Quick crystallization and
selectivity
Long reaction times, can
take up to few days
Controllability of product Less uniformity in final
product
Controllable process and
process outputs
Good control of product
specifications
Environment Chemical treating
procedures produce
hazardous waste.
Micro-wave heating
produces dangerous
fumes from volatile
chemicals
Waste treatment is
minimal.
Safety risks Safety procedure
requirements are high.
The use of microwaved
processes require high
caution and safety
procedures.
Regular safety procedures
are required, nothing of
high concern.
Commercialization High cost, hence and
obstacle for
commercializing
High manufacturing risks,
no commercial scale
process yet seen light
High demand product,
several tech companies
show interest
Scalability and
Technological Maturity.
Regular replacement of
main equipment
components for this
process
High concern regarding
hindered reproducibility
caused by varying
reaction conditions
At lab scale,
reproducibility has been
proven feasible
Economical profitability Not yet commercialized,
financial indicators not
available
Not yet commercialized,
financial indicators not
available
Proven technology in
small scale, financial
indicators are positive
27
Table 8: Process Selection Matrix based on risk and value assessment according to aspect weight on process.
Aspect (Risk Weight,
Value Weight)
Selection Criteria
Process
Electrochemical
Synthesis
Microwave synthesis Solvothermal Synthesis
Risk Value Risk Value Risk Value
Reaction Time (0.08,0.10) 4 4 3 3 2 2
Specification Control
(0.15,0.05)
4 1 3 3 4 5
Environment (0.04,0.05) 2 2 3 4 4 4
Safety (0.02,0.02) 2 2 3 2 4 4
Scalability (0.2,0.15) 1 1 1 1 4 4
Product Demand
(0.14,0.3)
3 4 1 2 4 5
Energy Usage
(0.12,0.0.08)
3 3 3 2 5 5
Proven (0.2,0.2) 1 2 1 2 5 4
Capital Cost (0.05,0.05) 1 4 1 3 3 2
Overall Score 2.27 2.78 1.82 2.15 4.11 4.13
28
Figure 5: Risk and Value four quadrant evaluation for the three processes.
Furthermore table 10 (see appendix) summarizes the grade point (out of 5) given by the five
research team members based on thorough research summarized in the literature review section.
The overall comparison of all three processes determined that the solvothermal synthesis process
is the most favored due to the high controllability aspect of the product along with less
environmental concerns regarding waste and by products. Also, financial indicators show that the
solvothermal process can be a profitable one.
Electrochemical Synthesis
Microwave Assisted Synthesis
Solvothermal Synthesis
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Low
V
alu
e
H
igh
High Risks Low
Risk vs. Value
29
2.7 Maximum Potential Profit
As a primary high level evaluation of economic viability, product and precursor prices will be
considered in order to determine maximum potential profitability. A value of $15 per kilogram
will be tentatively placed on the MOF product. Since Enovex’s product is 2-3 times as effective
as existing technologies, the product value may be reevaluated depending on the results of future
economic analysis. The raw materials used are listed in the following table along with their
corresponding prices.
Table 9: Raw Material Prices.
Type of Raw Material Raw Material Price ($/Kg)
Metal Salt (Soluble Metal) Zinc Nitrate 0.50
Ligand (Linker/Spacer) Terephthalic Acid 1.20
Solvent (Reaction Medium) N,N-diethylformamide 1
A calculation is included in the appendix of a basic mass balance around the primary reactor. The
reaction equation for MOF 5 is used and a specified percent conversion of 95%. Selling price per
kilogram of product is subtracted from the sum of the industrial market values of all reactants used
in the process. Through calculation it was determined that 100 kilograms of MOF product could
yield a maximum potential profit of $1027.50.
30
3.0 Base Case Design
The BFD below outlines the overall process with stream lines and major components of the
process. Initially streams of raw materials (benzenedicarboxylic acid and hydrated salt) are
introduced to batch reactor that operates at 1000C and pressure to be determined based on the
vapor pressure of the reactants. An outlet stream flows from the reactor to the filter section of
the process where the liquid slurry from the reactor is filtered and washed via methanol using
a pressurized filter vacuum. Proceeding the filtration process a vacuum dryer is used to further
eliminate moisture from the cake. After drying, soaking the cake with methanol to further
dissolve the DEF from the main structure of the MOF. A second filtration step is required after
the soaking process. (Adedibu & Isaac, 2012)
After the final filtration process, MOF-5 is tested using a Powder Diffraction X-ray device to
ensure stability of MOF-5 and that the pore volumes meet the expected dimensions for optimal
separation functionality. (Adedibu & Isaac, 2012)
Once the MOF has been tested for quality, it is subjected to the activation phase where the
stability and porosity of the MOF are reinforced (Adedibu & Isaac, 2012).
A preliminary mass balance can also be viewed in the appendix.
31
Figure 6: Proposed BFD
32
3.1 Pre-activation process
3.1.1 Reactor process and chemistry
R-100 is the major reactor proposed for the MOF manufacturing plant. The reactor will run in
batch mode and is similar to an autoclave. Solvents are brought to temperatures well above their
boiling points by the increase in self-generated pressures resulting from heating. The resulting
solvothermal process is proven and has precise control.
Figure 7: A Graphical representation of a typical Autoclave.
For the synthesis of microcrystals of MOF-5, mixture of an appropriate spacing ligand and a metal
precursor in N,N-diethylformamide (DEF) solvent are mixed.
3H2BDC + 4Zn(NO3)2•4H2O Zn4O(BDC)3•(DEF)7 + 7H2O
In the synthesis, a measured amount of benzenedicarboxylic acid (H2BDC) and Zn(NO3)2.4H2O is
dissolved in N,N-diethylformamide (DEF) resulting in a clear solution containing MOF-5, DEF
solvent and water (Strachan, et al., 2010).
The bound DEF of the post reaction product will be removed during the methanol soaking process
to result in a chemical compound of the form: Zn4O(BDC)3.
Stainless steel autoclave (1) Precursor solution (2) Teflon liner (3) Stainless steel lid (4) Spring (5)
33
3.1.2 Filtration
The filtration process is a very important part of the overall process since our product is moist
sensitive and it is critical to remove all the water coming from the product (See reaction equation
in section above) (Heinsmann, 1990) (Adedibu & Isaac, 2012).
The input to the filtration system includes unreacted raw material such as the hydrated salt and
benzenedicarboxylic acid along with the diethyl formamide (DEF). During the filtration process
the major components being removed are water and the solvent DEF. It is of utmost importance to
control the pressure of the vacuum filtration in order to avoid any damage to the crystal structure
of MOF-5. Also during this process the filtered product is washed with methanol to remove most
of the DEF solvent.
3.1.3 Drying
The drying process involves further removal of water at low pressure vacuum suction using and
industrial dryer. The pressure applied mustn’t exceed levels that would damage the crystal
structures of MOF-5 (Adedibu & Isaac, 2012) (Heinsmann, 1990).
3.1.4 Soaking
The resulting crystals from the drying process are to be soaked with methanol to dissolve the DEF
from the crystals and prepare the MOF for the final step of drying (Walton, 2013) (Adedibu &
Isaac, 2012).
34
3.1.5 Filtration
After the soaking process further filtration following the same filtration mechanism in the previous
section. In this filtration process lower vacuum pressure is required since MOF-5 is at the final
stages to be tested for pore volume and stability of structure. (Heinsmann, 1990)
3.1.6 Recycle Streams
Due to the high price of solvents and washing materials (DEF and methanol), recycling streams
were added to the process. This addition will ensure the reduction of waste, and also help reduce
the cost of the solvent and washing material.
3.2 Activation Process
Commissioning is a process by which the quality of the MOF can be tested and controlled. This
stage can be of great importance as it is used to identify any problem that may exist in the overall
process.
The Powder Diffraction X-ray (PDXR) is used to determine the structural characteristics of the
produced MOF’s. Samples of the MOF from the pre-activation process is sent through the PDXR
device to verify that the pore volumes and structure of the MOF meet the expected
specifications. Upon verifying the product specifications, the MOF produced will be ready for
the activation stage.
The tested MOF is then sent through the activation stage to ensure permanent porosity, without
compromising the structure of the MOF. Through the application of heat under vacuum the
35
trapped methanol will be removed in order to achieve a porous MOF material (Adedibu & Isaac,
2012) (Walton, 2013).
3.3 Innovation
3.3.1 Process control and data analysis
The ability to control a process is highly dependent on a detailed understanding of the system
behavior. Advances in sensor technology such as high speed cameras and thermal imaging are
providing new levels of information for process modeling in cost effective ways. We now have
access to continuous and distributed data instead of single point measurements. Moreover, the rate
of data generated and stored has exploded in the last few years. Extracting useful information from
process data is not a trivial task and requires complex data analysis techniques.
Today’s world is far from linear and far from simple. MIMO (Multiple-Input-Multiple-Output)
systems are processes that have numerous components that can interact in complex ways.
Traditional engineering approaches focus on linearization and decoupling of these complexities.
The solution used in our process will rise to the challenge by integrating advanced sensor
technology with state-of-the-art data analytics and proprietary control algorithms to achieve better
levels of process performance.
The proposed software solution for our plant will be called Industrial Internet of Things. A patented
multi-dimensional non-linear software algorithm that would leverage ‛‛big data’’ information from
industrial equipment and then based on the algorithm’s optimization capability, it will provide
36
control input into the key devices that operate the manufacturing process. The end result would be
a more efficient manufacturing operation, with improved productivity, increased quality, and
lower costs (Everett, Dubay, & McKillop, 2013).
3.3.2 Solvent Recycling
A large proportion of DEF solvent is required as reaction medium since, even at the elevated
temperatures used in the reactor, the BDC ligand has limited solubility. Solvent recovery is a
necessity both from an economic and environmental perspective. Post reaction the DEF and
water mixture can be largely separated from the MOF product before the methanol wash. It is
proposed that the use of a drying agent be investigated to separate the DEF from the water of
reaction. The Merck data tables list distillation as well as CaH2 and molecular sieves as suitable
DEF drying methods. The methanol used for post reaction washing and the DEF can be kept
from mixing, for the most part, by running the post reaction DEF/water filtrate into a separate
receiver than will be used to hold the methanol wash filtrate. The primary objective of solvent
recycling will be to remove the water of reaction. Separated and dried solvents will be stored in
holding tanks, where they can then be feed back into the process feed streams as needed (Merck,
2005).
37
3.4 Health, Safety and Environmental Considerations
3.4.1 Health and safety
The most important aspects with regards to a process are health and safety. Due to the application
of hazardous and flammable raw materials, safety codes and standards will be addressed
throughout the course of the design of the process. One of the most adequate means of analyzing
and identifying the hazardous sections of the process is known as Hazard and Operability
(HAZOP). This is one of the most effective and efficient means of identifying and analyzing
potential accidents in processes involving hazardous chemicals. It is also used to develop the
means to minimize risks associated with hazardous materials. Some methods to mitigate the health
and safety issues include the following:
Due to the hazardous and flammable nature of materials being used, employees will need
to follow proper safety protocols in order to ensure their safety.
Installation of additional conveyor belt systems to ensure the smooth flow of the process.
This will ensure the continuous production of the MOF.
Installation of additional equipment to account for redundancies. This will also ensure the
continuous production of the MOF.
Identification of the most hazardous sections in the overall process and ensure the proper
training of the employees involved.
Conduct maintenance drills for all the equipment on a regular basis. This will prevent any
problems associated with equipment.
The process will be installed with pressure and temperature relief systems to avoid temperatures
or pressures outside the process limits. This will help establish a safe workplace.
38
3.4.2 Environmental
One of the major factors that influences the design of the process are the issues with regards to the
environment. Since this particular process deals with chemicals that are harmful to the
environment a number of safety measures will prove to be a necessity. Since this process deals
with hazardous and flammable material, therefore measures will be needed to be taken to ensure
the safe handling of the hazardous wastes. Some of the means to ensure the safe handling of the
wastes include:
The methanol waste can be treated and recycled back into the process to reduce the overall
hazardous wastes. This will reduce the overall flammable properties of the waste.
The hazardous waste can be treated to make it environmental friendly and then disposed in
the environment. This process is known as land treatment.
39
4.0 References
Adedibu , T. C., & Isaac, A. Y. (2012). Synthresis and Applications of Metal Organic Frameworks
Materials: A Review. Acta Chimica & Pharmaceutica Indica, 75-81.
Ahmed, I., Jeon, J., Khan, N. A., & Jhung, S. H. (2012). Synthesis of a Metal–Organic Framework, Iron-
Benezenetricarboxylate, from Dry Gels in the Absence of Acid and Salt. Crystal Growth and
Design.
Aldrich, S. (2013, 10 19). BASF Pricing. USA.
Everett, S., Dubay, R., & McKillop, J. (2013, 11 6). Intelligent Controls. Retrieved from Eigen Innovation:
http://www.eigan.co/
Heinsmann, B. (1990). Heuristics in Chemical Engineering. Boston: Butterworth Heinsmann.
Jacoby, M. (2008, August 25). Heading To Market With MOFs. Chemical and Engineering News.
Jhung, S. H., Chang, J.-S., Hwang, J. S., & Park, S.-E. (2003). Selective formation of SAPO-5 and SAPO-34
molecular sieves with microwave irradiation and hydrothermal heating. Microporous and
Mesoporous Materials.
Jhung, S. H., Lee, J.-H., Yoon, J. W., Hwang, J.-S., Park, S.-E., & Chang, J.-S. (2005). Selective crystallization
of CoAPO-34 and VAPO-5 molecular sieves under microwave irradiation in an alkaline or neutral
condition. Microporous and Mesoporous Materials.
Kang, K.-K., Park, C.-H., & Wha-Seung, A. (1999). Microwave preparation of a titanium-substituted
mesoporous molecular sieve. Catalysis Letters.
Kerner, R., Palchik, O., & Gedanken, A. (2001). Sonochemical and Microwave-Assisted Preparations of
PbTe and PbSe. A Comparative Study. Chemistry of Materials.
Kim, J., Hye-Young Cho, & Wha-Seung Ahn. (2012). Synthesis and Adsorption/Catalytic Properties of the
Metal Organic Framework CuBTC. Catalysis Surveys from Asia.
Merck. (2005, 08). Drying agents. Retrieved from Merck Data Tables: http://www.mercury-
ltd.co.il/admin/userfiles/image/Information/Drying%20Agents.pdf
Oliveira, M. M., Schnitzler, D. C., & Zarbin, A. J. (2003). (Ti,Sn)O2 Mixed Oxides Nanoparticles Obtained
by the Sol−Gel Route. Chemistry of Materials.
Seda , K., & Seda, K. (2011). Biomedical Applications of Metal Organic Frameworks. Industrial &
Engineering Chemistry Research.
40
Strachan, D., Chun, J., Henager, C., Matyas, J., Riley, B., Ryan, J., & Thallapally, P. (2010). Summary
Report for the Development of Materials for Volatile Radionuclides . Washington : US.
Department of Energy Waste Forms.
Walton, M. S. (2013, 09 25). CEO. (A-consulting, Interviewer)
Wilkins, D. F. (2012, 08 15). MSDS. Retrieved from PromoChemOnline: promochemonline.com
Yaghi, O. M., O'Keeffe, M., Cordova, K. E., & Furukawa, H. (2013). The Chemistry and Applications of
Metal-Organic Frameworks. California: Science Magazine.
Yang, F. X. (2006). Inorganic Solvents. European Journal Inorganic Chemistry, 2229.
Yu, C. J. (2005). Crystallization Growth. Solid State Chemistry, 178,321.
41
5.0 Appendix Table 10: Process aspect grading points.
Process (Row)
Aspect (column)
Electrochemical synthesis
Micro-wave assisted
synthesis
Solvothermal synthesis
Member’s 1st
name initial
W S Y O L Av
era
ge
W S Y O L Av
era
ge
W S Y O L Av
era
ge
Reaction time 4 5 3 3 4 3.8 5 4 5 5 4 4.6 2 3 2 2 3 2.4
Controllability of
product
2 3 1 2 3 2.2 3 4 3 3 4 3.4 3 5 4 5 5 4.4
Environment and
safety
3 1 2 3 3 2.4 2 1 2 2 3 2.0 3 4 3 3 4 3.4
Commercializatio
n
1 2 3 2 1 1.8 2 2 1 1 1 1.4 4 3 5 5 3 4.0
Reproducibility 2 3 4 2 3 2.8 1 1 1 2 1 1.2 4 3 5 3 3 3.6
Economical
profitability
1 2 1 1 2 1.8 2 1 1 1 2 1.4 3 4 4 3 3 3.4
Overall average 3.0 2.8 4.2
Recommended