Porous Ceramic Membrane Reactor Research Articles

Photocatalytic degradation of amoxicillin via TiO2 nanoparticle coupling with a novel submerged porous ceramic membrane reactor

A combination of photocatalysis and membrane separation technology is applied to the degradation of refractory antibiotic organic compounds in aqueous solutions. TiO2 photocatalysts, which are inexpensive, commercially available, and nontoxic, have lately been of wide concern. In this study, a submerged ceramic membrane photocatalytic reactor (SCMPR) coupling with a suspended TiO2 photocatalyst was designed and developed for removing antibiotics in environmental water remediation. Separation of the TiO2 photocatalyst was carried out via antifouling ceramic membranes with hollow structures. The SCMPR had high removal capacity and stability for amoxicillin (AMX) degradation over a wide pH range, i.e., 6.5 to 9.0. The unique hollow structure of the ceramic membranes and aeration system not only provided high self-purification capability, but also enhanced the removal stability, of the SCMPR. As a result, SCMPRs are promising wastewater processing devices for practical application. Two possible pathways for AMX photodegradation in the SCMPR were analyzed by means of a Q-TOF LC/MS system, with most of the intermediates finally mineralized to CO2, water, and inorganic ions by hydroxyl radicals.

Economic evaluation of pre-combustion CO2-capture in IGCC power plants by porous ceramic membranes

Pre-combustion-carbon-capture is one of the three main routes for the mitigation of CO2-emissions by fossil fueled power plants. Based on the data of a detailed technical evaluation of CO2-capture by porous ceramic membranes (CM) and ceramic membrane reactors (WGSMR) in an Integrated-Gasification-Combined-Cycle (IGCC) power plant this paper focuses on the economic effects of CO2-abatement. First the results of the process simulations are presented briefly. The analysis is based on a comparison with a reference IGCC without CO2-capture (dry syngas cooling, bituminous coal, efficiency of 47.4%). In addition, as a second reference, an IGCC process with CO2 removal based on standard Selexol-scrubbing is taken into account. The most promising technology for CO2-capture by membranes in IGCC applications is the combination of a water gas shift reactor and a H2-selective membrane into one water gas shift membrane reactor. For the WGSRM-case efficiency losses can be limited to about 6%-points (including losses for CO2 compression) for a CO2 separation degree of 90%. This is a severe reduction of the efficiency loss compared to Selexol (10.3% points) or IGCC–CM (8.6% points). The economic evaluation is based on a detailed analysis of investment and operational costs. Parameters like membrane costs and lifetime, costs of CO2-certificates and annual operating hours are taken into account. The purpose of these evaluations is to identify the minimum cost of electricity for the different capture cases for the variation of the boundary conditions. Fixing 90% CO2 separation the analysis identifies clearly that the economic minimum for cost of electricity and maximum thermodynamic efficiencies do not coincide. The cost of electricity for the reference case was 67€/MWh and for the WGSMR integration with 90% CO2 separation 57€/MWh, if certificate costs of 30€/tCO2, membrane costs of 300€/m2 and 8000 operating hours/year are considered. Further studies on the sensitivity of cost of electricity on the technical and commercial boundary conditions will be presented.

ChemInform Abstract: Progress on Porous Ceramic Membrane Reactors for Heterogeneous Catalysis over Ultrafine and Nano‐Sized Catalysts

AbstractReview: 75 refs.

3D Simulation of fatty acid methyl ester production in a packed membrane reactor

The current work is aimed to simulate the production of high quality fatty acid methyl ester (biodiesel) production from palm oil in a micro porous ceramic membrane reactor. The TiO2/Al2O3 ceramic membrane was used as the separator and catalytic bed. It was packed with potassium hydroxide catalyst supported on palm shell activated carbon. The investigation of component distribution within the system was not possible. Hence CFD analysis was used to predict the distribution of the fatty acid methyl ester and the other by-products in the membrane module. The Brinkman equation was used to simulate fluid flow within the porous media. In addition, the Maxwell–Stefan equation was applied for simulation of reaction kinetics and mass transfer. The combination of the mentioned models was solved mathematically by means of the finite element method and PARDISO algorithm. In addition, the effect of temperature on transesterification reaction has been examined. The CFD results were indicated that increasing the reaction temperature leads to the same conversion in shorter time, or increase in temperature by 10°C, results in 5% growth of reaction for the same time period. The molar concentrations of each component are also shown in the total system for 85s and 400s. As we see from the diagrams, the simulated liquid velocity within the system reaches agreement with experimental results at 8.1% deviation and 0.61% overestimation in the reaction part.

Progress on Porous Ceramic Membrane Reactors for Heterogeneous Catalysis over Ultrafine and Nano-sized Catalysts

Heterogeneous catalysts with ultrafine or nano particle size have currently attracted considerable attentions in the chemical and petrochemical production processes, but their large-scale applications remain challenging because of difficulties associated with their efficient separation from the reaction slurry. A porous ceramic membrane reactor has emerged as a promising method to solve the problem concerning catalysts separation in situ from the reaction mixture and make the production process continuous in heterogeneous catalysis. This article presents a review of the present progress on porous ceramic membrane reactors for heterogeneous catalysis, which covers classification of configurations of porous ceramic membrane reactor, major considerations and some important industrial applications. A special emphasis is paid to major considerations in term of application-oriented ceramic membrane design, optimization of ceramic membrane reactor performance and membrane fouling mechanism. Finally, brief concluding remarks on porous ceramic membrane reactors are given and possible future research interests are also outlined.

Influence of geometrical and operational parameters on the performance of porous catalytic membrane reactors

In this study, porous membrane reactors with various characteristic length (inner diameter), controllable catalyst support thickness, active catalyst surface area and tunable wetting properties are described for heterogeneously catalyzed gas–liquid–solid (G–L–S) reactions. We developed porous ceramic membrane reactors (Al2O3) with various geometrical parameters and applied these to a model G–L–S reaction. Integration of a catalyst support layer (γ-Al2O3), catalyst deposition (palladium) and surface modification (hydrophobization) steps were carried out to tailor these tubular porous ceramic reactors. These reactors were tested for catalytic hydrogenation of nitrite ions (NO2-) in water for different initial concentrations and flow rates. In addition, to improve the external mass transfer in the liquid phase, we integrated additional slug flow in our porous reactors, merging the advantages of both dispersed phase and membrane reactor operation. Results showed that the NO2- reaction rate per Pd-catalyst decreased with increasing thickness of the catalyst support layer, indicating internal mass transfer limitations. Reducing the inner diameter of the reactor and also integration of slug flow enhanced the performance by improving its external mass transfer.

Multiobjective Optimization of a Porous Ceramic Membrane Reactor for Oxidative Coupling of Methane

Multiobjective optimization of a porous ceramic membrane reactor for oxidative coupling of methane has been studied with the elitist nondominated sorting genetic algorithm with jumping genes (NSGA-...

A comparative simulation study of methane steam reforming in a porous ceramic membrane reactor using nitrogen and steam as sweep gases

Comparative studies were carried out via numerical simulation to analyze the performances of a porous ceramic membrane reactor for methane steam reforming using nitrogen and steam as sweep gases. A one-dimensional pseudo-homogeneous model taking into account the thermal effect was used to describe the behavior of the membrane reactor. As a result, the use of steam as the sweep gas showed the better performance in terms of methane conversion and hydrogen recovery yield, for most of the operating parameters investigated including the reaction temperature, the feed flow rate, as well as the sweep gas flow rate and the operation mode. The counter-current flow mode was found to perform better than the co-current flow mode for both nitrogen and steam as the sweep gases under the conditions considered.

Optimal design and operation of methane steam reforming in a porous ceramic membrane reactor for hydrogen production

Multi-objective optimization is performed for methane steam reforming in a porous ceramic membrane reactor using nitrogen and steam as sweep gases. The non-dominated sorting genetic algorithm (NSGA) is applied in solving the optimization problems. The Pareto optimal solutions have been obtained for the simultaneous maximization of the hydrogen production rate and the recovery yield, and for the simultaneous maximization of the hydrogen production rate and minimization of the sweep gas flow rate or the membrane area. The comparisons of the membrane reactor performances for nitrogen and steam as sweep gases at optimal conditions illustrate that the use of steam as a sweep gas can produce more hydrogen at higher recovery yield, or produce more hydrogen using less sweep gas or membrane area.

06/01325 Simulation of a porous ceramic membrane reactor for hydrogen production: Ohmori, W. Y. T. et al. International Journal of Hydrogen Energy, 2005, 30, (10), 1071–1079

06/01325 Simulation of a porous ceramic membrane reactor for hydrogen production: Ohmori, W. Y. T. et al. International Journal of Hydrogen Energy, 2005, 30, (10), 1071–1079

Simulation study on ceramic membrane reactor for hydrogen production

A simulation study was carried out to elucidate the effects of membrane properties in terms of permeability and selective permeability on the design parameters of a porous ceramic membrane reactor for hydrogen production. The reaction involved was methane steam reforming. The design and operating parameters of the membrane reactors associated with four sets of membranes with different permeabilities were determined to achieve both the hydrogen production rate of 1 m3/h (stp) and the recovery efficiency of 80% at 773 K. It was found that less membrane area was required when a membrane with higher permeability value was used. However, a membrane with a higher selective permeability for hydrogen should be used if the purity of hydrogen is also regarded as one of the process objectives. The sensitivities of the main operating parameters to the reactor performance were also investigated and discussed.

Simulation of a porous ceramic membrane reactor for hydrogen production

A systematic simulation study was performed to investigate the performance of a porous ceramic membrane reactor for hydrogen production by means of methane steam reforming. The results show that the methane conversions much higher than the corresponding equilibrium values can be achieved in the membrane reactor due to the selective removal of products from the reaction zone. The comparison of isothermal and non-isothermal model predictions was made. It was found that the isothermal assumption overestimates the reactor performance and the deviation of calculation results between the two models is subject to the operating conditions. The effects of various process parameters such as the reaction temperature, the reaction side pressure, the feed flow rate and the steam to methane molar feed ratio as well as the sweep gas flow rate and the operation modes, on the behavior of membrane reactor were analyzed and discussed.

Optimum operation of oxidative coupling of methane in porous ceramic membrane reactors

This paper presents analysis of oxidative coupling of methane on Li/MgO packed porous membrane reactor (PMR) by the fixed-bed reactor (FBR) model with reliable reaction kinetic equations. PMR can improve the selectivity and yield by controlling the oxygen feed to the catalyst bed through manipulating the feed pressure. At a fixed methane feed rate there is an optimal oxygen feed pressure that will achieve the highest yield. With a commercial ultrafiltration ceramic membrane, theoretical analysis shows that PMR can achieve, by operating with both side pressures at 1 bar at 750 °C, a maximal 30% yield at 53% selectivity. The maximal yield achieved in the FBR of identical dimension and temperature is 20.7% at 52.5% selectivity. Parametric study shows that lowering the membrane permeability improves the performance. Higher oxygen feed pressure will reduce the yield as well as the selectivity. Homogeneous reactions at high shell-side pressure can have adverse effect on the performance due to the fact that homogeneous reaction rates are strongly pressure dependent. The shell (oxygen feed) side volume must be minimized to reduce the homogeneous reactions. The results of PMR model calculation fit the published experimental result unexpectedly well.

Comparing kinetic design of propene partial oxidation between a CsAg and a ReAg immobilized membrane reactors

The efficiency of the partial oxidation of propene (PP) to propylene oxide over a CsAg and a ReAg catalysts immobilized in two porous ceramic tube membrane reactors (designated Cs-membrane and Re-membrane respectively) was compared by using three different flow reactors (convection flow (CFR), diffusion flow (DFR) and plug flow (PFR) reactors). In the Cs- and Re-membranes, the CFR was commonly designed as the best efficient reactor at 420–524 K and, as a common reaction kinetics, two steady state rate equations, for the production of propylene oxide (PO) and CO 2 were separately proposed by two different reaction pathways. The reactor efficiency of CFR for the PO production selectivity was evaluated as 11.2–17.5% for the Cs-membrane reactor and 18–75% for the Re-membrane reactor because of an advantage of PO production rate constant as a rate determining step, which was effectively regulated by the amount of a stable intermediate formed on the catalyst surface in a CO 2 formation pathway.

Methane oxidative coupling using porous ceramic membrane reactors—I. reactor development

A new reactor concept has been developed and tested for the conversion of methane into ethane, ethylene and higher hydrocarbons via oxidative coupling. The basic idea consist of providing a low oxygen concentration in the reactor in order to increase hydrocarbon selectivity. To this end, oxygen is supplied to the reacting mixture by permeation through a porous wall, which is capable to withstand the temperatures and pressures involved, and at the same time give adquate values of oxygen flux. In this part, the main requirements of this type of reactor are discussed, as well as some operational constraints. The modifications carried out on the starting ceramic membranes are described and their properties are characterized at different stages of the process.