Papers by Keyword: Membrane Reactor

Abstract: In this paper we found two catalysts exhibit high catalytic activity and stability during the partial oxidation of methane (POM) in Coke oven gas (COG) in BCFNO membrane reactor. Such as the NiO/MgO catalyst, we discussed the COG and air flow rate on the performance of reforming of COG. The results show that the NiO/MgO catalyst exhibits high activity. The experimental result of the CH₄ conversion, selectivity of H₂ and CO were suited well to the result of thermodynamic analysis. And the LiNiCeO/γ-Al₂O₃ catalyst, we discussed the LiNiCeO/γ-Al₂O₃ catalysts with different amount CeO₂ in order to compare the reaction performance on the membrane reactor. The results show that the oxygen permeation flux increased significantly with increasing the amount of CeO₂ during the POM in COG. Such as, the LiNi15%CeO/γ-Al₂O₃ catalyst with a oxygen permeation flux of 10.6 ml⋅cm^-2⋅min^-1 and a 100% CH₄ conversion were obtained at 875 oC.

Abstract: An advanced membrane reformer system for hydrogen production from natural gas has been developed and demonstrated its long-term durability. A pilot-scale membrane reformer system, of which capacity is 40 Nm³/h, has been developed with membrane reactors consist of Pd-based thin hydrogen separation membranes and reforming catalyst beds. The system, which has already achieved a significant hydrogen production efficiency of 81.4% (HHV), has been operated for 8000 h and demonstrated its durability. A scale up analysis was also carried out for the purpose of estimating the efficiency of a commercial-scale system with a capacity of 300 Nm³/h using a process simulator and actual operation data obtained from the pilot system. The hydrogen production efficiency of the 300 Nm³/h system was estimated to be 82.9% (HHV).

Abstract: In this work, a modified two-step reaction kinetics model for methane-oxygen combustion is used to predict oxy-combustion characteristics and permeation rate characteristics inside a stagnation flow simple symmetric ITM reactor. New coefficients oxygen permeation equation model is introduced herein this work by fitting the experimental data available in the literature for a LSCF-1991 ion transport membrane. Using CH4 as fuel plus CO2 as sweep gas, the effects of reactivity is analyzed using the same sweep gases (CH4 plus CO2) is investigated here by comparing the same cases with and without considering reactions in the permeate side. Also the influences of the percentage of CH4 in the sweep gases mixture on the permeation and combustion processes are included in this work. It was found that the oxygen permeation flux increases with activating chemical reactions in the permeate side of the membrane and this is due to increased partial pressure driving force across the membrane surface as a result of disappearance of oxygen molecules in the permeate side because of combustion. Another reason for this is the increase in the membrane temperature which affects the activation energy of the membrane and so the permeation rate. More details about the models used and the oxy-fuel combustion characteristics in the permeate side of the membrane are included in the present study.

Abstract: This work is aiming to investigate the dependence of the performance of a 3-D ITM reactor depends on the operating conditions and flow configuration. This work is a design problem, where the oxygen separation requirements of the ITM reactor are specified, and then the reactor is designed to meet them. The effect of subdividing the total reactor length into a number of parallel subunits rather than only one unit on the flow characteristics and membrane stability is studied. The results indicate that the average wall temperature is higher in the case of counter current flow than in the case of co-current flow; this is attributed to the effective heat transfer in the case of counter-current flow, and as a result, the average partial pressure driving force was found to be much lower in the case of counter current flow in order to get the same average flux for both flow configuration. The present results indicate that the use of parallel design instead of series design will result in shorten the channel length, reduce pressure drop through the system and will result in more stable operation of the membrane. Also, this design takes the benefit of high oxygen permeation flux at channel inlet which will reduce the total size of the reactor.

Abstract: Nanometer photo catalytic-membrane reactor integrated photo catalytic technology with membrane separation technology was applied to remove virus existing in water. Bacteriophage f2 was used as surrogates for human enteric viruses. Two kinds of nanomaterials (TiO₂ and ZnO) were selected as the catalyst. Three kinds of membranes interception performance for virus, adsorption efficiency of nanomaterial for virus, inactivated effect for virus with photo catalysis, and the comprehensive effect to f2 of photo catalytic-membrane reactor were studied under the transmembrane pressure of 20Kpa, with nanomaterial concentration of 100mg/L, light dose of 20mJ/cm2. It showed that the interception effect of flat membrane with casting was the best. the adsorption efficiency of the two kinds of nanomaterials was different, 1.478 lg and 0.201 lg for TiO₂ and ZnO, respectively. The removal effect of the photo catalytic oxidation system to f2 was similar, both in 2-3 log. The removal efficiency of the photo catalytic-membrane reactor system has no obvious difference, both in 3-4 log, and it is improved significantly compared to the effect of individual photo catalysis and membrane separation. Further research indicates that: the elimination function of coupling system to f2 includes UV-inactivated, adsorption of nanomaterials, the inactivation of nanomaterials, the effect of oxide moiety which formed after nanomaterials absorbing ultraviolet light and membrane retention.

Abstract: Oxygen-permeable perovskite ceramics with mixed ionic-electronic conducting properties can play an important role in the high temperature separation of oxygen from air. Such membranes are envisaged for application in catalytic membranes reactors and in oxy-fuel and pre-combustion technologies for fossil fuel power plants enabling CO2 capture. Since large-scale gas separation applications demand high membrane surface/volume ratios, membranes with capillary or hollow fiber geometry have a distinct advantage over tubular and flat sheet membranes. The fabrication and performance of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) capillary membranes is presented. The capillaries were made by a spinning technique based on phase inversion using a sulfur or non-sulfur containing polymer binder. Attention is given to the polymer solution and ceramic spinning suspension in order to avoid the formation of macrovoids and achieve gastight membranes. The comparison of the performance of sulfur-free and sulfur-containing BSCF capillaries with similar dimensions revealed a profound impact of the sulfur contamination on both the oxygen flux and the activation energy of the overall oxygen transport mechanism. In addition the effect of activation layers on oxygen permeation is studied.

Abstract: Under the same operating mode, the flux of non-bulking MBR（1#） descends much faster than the flux of filamentous bulking MBR（3#）, mainly because the particles adhered to membrane 1# become smaller much more quickly，provided that spherical particles tend to be rushed off into the mixed liquid more easily than filamentous particles. The falling of particles diameter is caused by the decline of flux, which can be interpreted with the formulation for critical diameter and flux as well as Critical Flux Theory.

Abstract: A cross-shaped pattern was formed on the surface of Ba_0.5Sr_0.5Co_0.8Fe_0.2 O_3−δ oxygen permeation membrane by laser ablation in order to increase the specific surface area of the membrane. The membrane was used to assemble a reactor for partial oxidation of methane (POM) to syngas in the present of Ni/ZrO₂ catalyst. The CH₄ conversion and CO selectivity of the membrane reactor can reach 98.8% and 91.5%, respectively, and the oxygen permeation flux through the membrane was 11.0 ml/cm² min at 850°C. The effect of space velocity (SV) on CH₄ conversion rate and CO selectivity in such reactor was discussed.

Abstract: A cross-shaped pattern was formed on the surface of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ oxygen permeation membrane by laser ablation in order to increase the specific surface area of the membrane. The membrane was used to assemble a reactor for partial oxidation of methane (POM) to syngas in the present of Ni/ZrO₂ catalyst. The CH₄ conversion and CO selectivity of the membrane reactor can reach 98.8% and 91.5%, respectively, and the oxygen permeation flux through the membrane was 11.0 ml/cm² min at 850°C. The effect of space velocity (SV) on CH₄ conversion rate and CO selectivity in such reactor was discussed.

Abstract: The performance of Ni/SiO2 Catalysts modified by La2O3, ZrO2 and CeO2 were tested in a BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membrane reactor by catalytic partial oxidation of coke oven gas (COG) under atmospheric pressure. The results show that the oxygen permeation flux increased dramatically with Ni/RxOy/SiO2 (R = La, Zr or Ce) catalysts by adding the element of rare earth especially the La during the reforming reaction. At optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 16.4 ml/cm2•min and a CH4 conversion of 99.2% have been achieved at 900 oC.