Bulu Pradhan, Department of Civil Engineering, for their valuable suggestions and contribution to my research work. I would also like to thank the faculty members at the Department of Chemical Engineering for their good cooperation during my project period in the department.
Sujoy Bose
On the basis of the aforementioned problem statement, this entire study together with the application of the manufactured catalytic membrane is divided into three segments. Finally, the application of the produced CMR ie. described the removal or recovery of elemental sulfur using catalytic membrane reactor as a function of catalytic activity (conversion, yield and selectivity) and mass transport study.
Published journals from this work
- Introduction and Objectives 1-44
- Aim and Objective of the present research 42-44 Chapter 2 Fabrication and Characterization of Low-cost Ceramic
- Membrane Parameter Optimization using Response
- Comparison with formerly published work 110-111
- Synthesis and Characterization of Catalyst 113-140
- Fabrication and Characterization of Low-cost Catalytic
- Performance of Catalytic Membrane and
- Overall Conclusions and Scope of Future Work 193-195
CR Concentration of feed gases present in the permeate (mol.m-3) Cs Reagent concentration on the outer surface of the catalyst (mol.m-3). Rint Reaction rate at the interface (mol.m-3.min-1) R1 Model response for membrane flexural strength R2 Model response for membrane porosity.
Greek letters
700 and (c) 850°C using optimized composition from CCD analysis 106 Figure 3.11 Effective permeability factor versus average pressure for the optimized. 154 Figure 6.1 CMR configuration for multi-component mass transport 160 Figure 6.2 Figure 6.2 Schematic diagram of the experimental setup [N.B.
Introduction and Objectives
Introduction
- Air pollutants, their sources and effects on human health
- Industrial sources and separation techniques
- Membrane separation processes
- Membrane reactors
- Classification of MRs based on their configuration
- Catalytic membrane reactor (CMR)
- Synergistic effect of separation and reaction
- Membrane functions in CMR and applications
- Opposite flow mode catalytic membrane reactors
- Fabrication of CMR
- Catalytic membrane reactors vs. traditional reactors
- Possible scopes for further research
In fact, by means of the so-called "displacement effect", the limitations of thermodynamic equilibrium can be overcome. Clause reactions are studied to realize. effect of reaction reversibility and pressure difference on gas mixture flow.
Aim and objectives of the present research
Firstly, the use of low-cost ceramic supports instead of the use of alumina-based costly supports will be promoted to reduce the production cost of the catalytic membrane reactor for various industrial applications. Verification of the performance of the prepared membrane reactor based on conversion, efficiency and selectivity. Estimation of the production costs of the catalytic membrane reactor in terms of support membrane costs, catalyst development costs and reactor die costs.
Validating the performance of the newly developed CMR by understanding multi-reactant mass transfer behavior and kinetics using a theoretical approach. Das, “Preparation and characterization of low-cost tubular ceramic support membranes using sawdust as a pore former,” Materials Letters.
Fabrication and Characterization of Low-cost Ceramic Support Membrane
- Selection and treatment of sawdust particle
- Membrane fabrication
- Characterization techniques
- Physical characterizations
- Three-point bend test
- Acid-alkali test
- Statistical analysis
The morphology and the chemical compositions of the raw and resulting samples (thermally and chemically modified) are investigated using SEM and EDX (LEO 1430VP®, Oxford). Volumetric porosities of all manufactured membranes are determined based on gravimetric analysis of water trapped in the pores of the membrane walls. The values of the slope and intercept obtained from the graph are used to evaluate the pore diameter and porosity of the membrane.
Where, S is the permeable area of the membrane (m2), Q is the volumetric flow rate (m3.min-1), P2 is the membrane pressure on the permeate side and ΔP is the trans-membrane pressure drop. The chemical stability of the fabricated ceramic membrane is also verified by immersing the membrane in acid (Conc. HCl, pH 2) and alkali (NaOH, pH 12) solutions for seven days.
Results and discussions
- Characterization of sawdust
- Effect of particle size of sawdust on the porosity and pore size of the membrane
- Thermogravimetric (TGA) analysis
- Functional group identification
- Compositional analysis and study of microstructures of modified sawdust
- Physical characterization of membranes screened through 44 B.S.S
The particle size distribution of both raw sawdust (cleaned through B.S.S and 100 mesh) and sample mixtures for membrane fabrication are shown in Figure 2.3 (a-f) respectively. Changes in the elemental composition of the sawdust throughout the process are revealed by the EDX study (refer to Figure 2.10). No such significant changes are observed in the elemental composition of alkali and acid-soaked sawdust (Figure 2.10b-c) compared to the elemental composition of raw sawdust (Figure 2.10a).
However, thermally modified sawdust samples (Figure 2.10d-f) show a slight change in elemental composition (presence of Cl, Br, Si, etc. as impurities) compared to raw sawdust samples. However, no such major deviations are observed in the elemental composition of alkali absorbed thermally modified sawdust samples, as shown in Figure 2.10g-i. a) Raw sawdust (b) Alkali-treated sawdust (c) Acid-treated sawdust.
- TGA analysis
- Effect of raw materials content on particle size distribution
- Determination of porosity using Archimedes’ principle
- Surface morphological analysis
- Pore size analysis built on FESEM images
- Phase identification by XRD analysis
- Permeation characterization of membrane screened through 44 B.S.S
- Determination of porosity and pore diameter via gas permeation
- Mechanical stability
- Chemical stability
- Summary
SM1, SM3 and SM4 exhibit mono peak, which implies smaller particle size of the raw materials. The nature of the particle size distribution curve as well as the average particle size in SM2 is affected due to the higher weight percentage of quartz. Weight loss of the ceramic membranes depends on the weight ratio between sawdust and other raw materials.
The effect of sawdust particle size, control of porosity and pore size, and the microstructure of the sawdust ceramic membrane are discussed. Two important parameters viz. the porosity and pore size of the produced membrane increase or decrease with the increase in the amount of sawdust due to the removal of lignocellulosic material.
Membrane Parameter Optimization using Response Surface Methodology (RSM)
Materials and methods
- Membrane fabrication
- Membrane characterization
- Three-point bend test
- Surface morphology
- Average pore diameter and porosity
- Acid-alkali test
- Response surface methodology via design of expert
According to the design expert, the binders range from 4.21% to 10.79% of the total weight of the raw materials (the total weight of the sample mixture is 40 g) and the cooking pressure applied to the sample mixture is varied from 7.23 MPa to 12 .39 MPa . Meanwhile, the porosity of the membrane is calculated using the volumetric porosity determination technique based on Archimedes' principle (Equation 2.1 in Chapter 2). The surface morphology and phase identification of the optimized membrane are analyzed by field emission scanning electron microscope (FESEM) (∑igma, Zeiss, USA) and X-ray diffraction (XRD), respectively.
A portion of the sample is cut into a small piece and mounted on an aluminum rod with carbon tape. The chemical stability of the fabricated composite membrane is verified by immersing the composite in the acidic (concentrated HCl, pH 2) and alkaline (NaOH, pH 12) solution.
A, Preparation
B, Amount of
C, Amount of
- Cost estimation
- Results and discussion
- Analysis of variance (ANOVA) and response surface
- Model verification on the basis of statistical analysis
- Optimization study
This section aims to understand the interaction between binder content and preparation pressure with membrane porosity and membrane (bending) strength using RSM's CCD. High flexural strength is achieved at high preparation pressure with higher amount of binders (see Figures 3.1a-c). It has been confirmed that the effect of SM is less significant on the bending strength of the membrane.
In Figure 3.2, the three-dimensional response surface plots show the influence of preparation pressure and binder content on membrane porosity. Figure 3.6a and b show the plots of the residuals against the predicted response for the membrane flexural strength and porosity respectively.
A, preparation
- Study of phase transformation and microstructure of the optimized membrane
- Gas permeation test of the optimized membrane
- Chemical stability test of the optimized membrane
- Cost analysis of the fabricated support membrane
- Comparison with formerly published work
- Summary
It is interesting to note that the permeability rate of the membrane sintered at 850 °C is reduced compared to the membrane. Ceramic porosity values during acid-base testing are also shown in Table 3.7. The manufacturing costs of manufactured ceramic membranes (disc and tubular forms), listed in previously published literature, are given in Table 3.10.
The morphological study of the optimized membrane shows a significant range of average pore diameter along with good chemical stability. These results suggest that the optimized membrane offers low membrane production cost (as little as $332/m2), along with good mechanical strength, morphology, and chemical stability.
Synthesis and Characterization of Catalyst
Materials and methods
- Chemicals for catalyst preparation
- Catalyst synthesis
Twenty-four numbers of Mo-Co/γ-Al2O3 samples (denoted SC1, SC2, SC3 and SC4) have been prepared via impregnation by mixing Mo, Co precursors and water to both high and low surface area γ-alumina supports to find out of the appropriate support material, optimum Mo content and calcination temp. Accurately weighed 20 g of catalyst (maintaining the weight percentage) has been prepared for this study. The support material is mixed with precursors and Millipore water maintaining a 1:1 water/solid ratio to obtain a slurry solution and kept at ambient temperature (28 ± 2°C) for 30 minutes to maintain sample homogeneity.
The sample is then placed in a muffle furnace and temperature is increased and held at 120°C for 9 hours to remove excess water from the solution and at three different calcination temperatures (350, 400 and 600°C) for 5 hours at a heating rate of 5°C/min. The catalyst compositions of different loadings of Mo and Co precursors with different synergistic ratios are given in Table 4.1.
Characterization techniques
- BET surface area analysis
- Particle size analysis
- Fourier Transform Infrared Spectroscopy (FTIR)
- X-ray diffraction (XRD)
- Field-emission scanning electron microscopy (FESEM)
- Electro spin resonance (ESR)
- H 2 Temperature programmed reduction (TPR)
- CO chemisorption
- Laser Raman spectroscopy (LRS)
- Transmission electron microscope (TEM)
The surface texture of the catalysts was analyzed by FESEM (Σigma, Zeiss, USA) operating at 3 kV. A small amount of the catalyst sample is placed on an aluminum pin with carbon tape coated with gold particles under vacuum, and then placed on the FESEM sample holder. ESR spectra of the catalyst sample (~ 30 mg) are taken at room temperature with JEOL, JES–.
The metal dispersion, metal surface area and active particle diameter of the catalysts are measured in a micromeritics® unit 1 (2720). After cooling to room temperature, the sample tube is transferred to the analysis port for reduction analysis of the sample.
Results and discussion
- Effect of support, Mo content and calcination temperature on metal dispersion and metallic surface area
- Identification of bimetallic oxide catalyst
- ESR-TPR of bimetallic oxide catalyst
- Verification of the presence of optimized crystalline catalyst
The spectrum of γ-Al2O3 (low surface area) supported SC1, SC2 and SC3 calcined at 600°C (Figure 4.1a) shows the presence of MoO3 at 663 cm-1, which refers to the asymmetric stretching mode of MoO42- tetrahedral. In Figure 4.2a, the band of MoO3 at 663 cm-1 has disappeared for the supported γ-Al2O3 catalyst (low surface area) calcined at 400°C since the IR spectrum of CoMoO4 contains only vibrations of MoO42-tetrahedral units, confirming. formation of CoMoO4 for γ-Al2O3 (low surface area) supported catalyst calcined at higher temp. For the supported γ-Al2O3 catalyst (high surface area), SC3 sintered at 400°C and all catalysts (SC1, SC2 and SC3) calcined at 600°C show the presence of β-CoMoO4 (see Figure 4.3) proving that γ- Al2O3 (high surface area) can form bimetallic oxide with metal precursors at lower and higher temperatures.
But no peak at 570ºC (curves d and e in Figure 4.9b) is observed for the alumina (high surface area) supported catalyst containing 12% Mo, calcined at 600ºC. The Raman spectra of alumina (high surface area) supported catalyst (SC3) calcined at 350, 400 and 600°C (Figure 4.11) show that the main phases of the optimized catalyst are MoO3 and CoMoO4.
MoO 3
- Summary
The catalyst prepared by depositing metal precursors via soaking impregnation on γ-Al2O3 surface (large surface area) has been shown to be superior to the γ-Al2O3 (small surface area) based catalysts in terms of morphology, metal dispersion and metallic surface area. Alumina (high surface area)-based catalysts exhibit a wide range of pore sizes along with high MD and MSA due to negligible particle accumulation or pore confinement, which can be useful for solid-catalyzed reactions. MD and MSA increase with increase in Mo content for the y-alumina (high surface area) supported catalyst. c) Higher calcination temperature causes cracks on the surface of the metal particles.
TEM images show a well-distributed dispersion of metal precursors throughout the support matrix. e) The optimal Mo content on aluminum oxide and the optimal firing temperature are 16 wt. Das, “Solid Lubricant-based Coating of Catalyst on the Surface of Tubular Ceramic Support for Catalytic Membrane Fabrication,” International Journal of Applied Ceramic Technology.
Fabrication and Characterization of Low-cost Catalytic Membrane
- Materials and methods
- Materials used
- Catalytic membrane fabrication method
- Characterization techniques
- Membrane surface morphology
- Film thickness measurement
- Phase transformation study
- Spectrophotometric analysis
- Cost estimation
- Results and discussion
- Determination of porosity of the coated membrane and thickness of the coated layer
- Surface morphology of coated membrane using FESEM image analysis
- XRD analysis
- FTIR analysis of coated membranes
- EDX mapping analysis
- Manufacturing cost evaluation
- Summary
Finally, a soft brush is used to remove loose MoS2 powder from the surface of the support membrane after heating (Figure 5.1b). A complete picture of porosity values of the catalyst coated membrane with and without binder and additive is shown in Figure 5.2. Porosity is determined as a function of water trapped in the pores of the membrane walls.
An absence of additive ensures loose interaction between the surface of the support membrane and the coated surface, which causes an increase in porosity. The presence of Al, Mo and Co throughout the membrane surface of all the coated membrane approves the presence of catalyst over the outer surface of the membrane.
