共查询到20条相似文献,搜索用时 46 毫秒
1.
《International Journal of Hydrogen Energy》2019,44(41):23107-23119
Traditionally, zeolite membranes were prepared using oven heating which usually resulted in lengthy synthesis time and thick membrane. Previous result indicated that oil-bath heating can significantly reduce the synthesis time and membrane thickness of SAPO-34 membrane due to the elimination of thermal-lag. SSZ-13 membrane was prepared using oil-bath heating method. Significant reduction on synthesis time (from 2 to 6 d to 2 h) and membrane thickness (from 5 to 10 μm–1.5 μm) were realized, which is the result of enhanced nucleation and crystallization from ultrafast heat transfer of oil-bath heating. Template removal was realized with an optimized rapid thermal processing method (O-RTP). Outstanding CO2-CH4 separation performance was obtained. The high permeance mainly comes from the thinner membrane. The high selectivity can be attributed to O-RTP, which strengthened the bonding between zeolite crystals and minimized thermal exposure time. The combination of oil-bath heating and O-RTP led to high performance SSZ-13 membrane. 相似文献
2.
Zhou Hong Feng SunDongdong Chen Chun ZhangXuehong Gu Nanping Xu 《International Journal of Hydrogen Energy》2013
MFI zeolite membranes were synthesized on porous α-alumina hollow fibers by in-situ hydrothermal synthesis. The membranes were further modified for H2 separation by on-stream catalytic cracking deposition of methyldiethoxysilane (MDES) in the zeolitic pores. The separation performance of the modified membranes was characterized by separation of H2/CO2 gas mixture at 500 °C. Activation of MFI zeolite membranes by air at 500 °C was found to promote catalytic cracking deposition of silane in the zeolitic pores effectively, which resulted in significant improvement of H2-separating performance. The H2/CO2 separation factor of 45.6 with H2 permeance of 1.0 × 10−8 mol m−2 s−1 Pa−1 was obtained at 500 °C for a modified hollow fiber MFI zeolite membrane. The as-made membranes showed good thermochemical stability for the separation of H2/CO2 gas mixture containing H2O and H2S, respectively. 相似文献
3.
H. Li J.A.Z. PieterseJ.W. Dijkstra J. BoonR.W. van den Brink D. Jansen 《International Journal of Hydrogen Energy》2012
This study investigated the water-gas shift reaction in a bench-scale membrane reactor (M-WGS), where three supported Pd membranes of 44 cm in length and ca. 6 μm in thickness were used, reaching a total membrane surface area of 580.6 cm2. The WGS reaction was studied with the syngas mixture: 4.0% CO, 19.2% CO2, 15.4% H2O, 1.2% CH4 and 60.1% H2, under high temperature/pressure conditions: T = 673 K, pfeed = 20–35 bar(a), pperm = 15 bar(a), mimicking CO2 capture with co-production of H2 in a natural gas fired power plant. High reaction pressure and high permeation of Pd membranes allowed for near complete CO conversion and H2 recovery. Both the membranes and the membrane reactor demonstrated a long-term stability under the investigated conditions, indicating the potential of M-WGS to substitute conventional systems. 相似文献
4.
《International Journal of Hydrogen Energy》2022,47(65):28025-28033
Using molecular dynamics (MD) simulations, we investigated the performance of graphenylene membrane with functionalized nanopore in the H2/CH4 separation. In the present work, we studied the impact of functionalized nanopore, system temperature (298, 323, and 348 K), applied difference pressure (up to 2 MPa), and feed composition on the H2/CH4 separation performance. The passage of gas molecules across the nanopore was monitored within the simulations, and the permeance was determined under applied conditions. The results revealed that the size of gas molecules and its interaction with the membrane nanopore are two important factors in the separation performance of H2/CH4 gas mixture. It is also found that H2 molecules can easily pass through the studied membranes, whereas no CH4 molecule was seen in the permeate side, which confirms the ultrahigh selectivity of H2 over CH4. Furthermore, the maximum H2 permeance of 1.95 × 105 GPU through the pore 1 was obtained at 1.5 MPa, which was higher than that of 1.93 × 105 GPU through pore 2. The results also demonstrated that the system temperature doesn't have any effect on the membrane performance. To this end, the permeance of H2 molecules through the studied membranes obviously increased with raising the ration of H2 molecules in the feed composition. Due to high selectivity and permeance, the graphenylene membrane with functionalized nanopore is expected to have promising applications in hydrogen separation from H2/CH4 mixed gas. 相似文献
5.
《International Journal of Hydrogen Energy》2020,45(51):27331-27345
Thermally robust membranes are required for H2 production and carbon capture from hydrocarbon fuel derived synthesis (syn) gas. Polybenzimidaole (PBI) materials have exceptional thermal, chemical and mechanical characteristics and high H2 perm-selectivity for efficient syngas separations at process relevant conditions. The large gas volumes processed mandate the use of a high-throughput, small footprint hollow fiber membrane (HFM) platform. In this work, an industrially attractive spinning protocol is developed to fabricate PBI HFMs with unprecedented H2/CO2 separation performance. A unique dope composition incorporating an acetonitrile diluent is discovered enabling asymmetric macro-void free PBI HFM fabrication using a water coagulant. The influences of dope viscosity, coagulant chemistry, and air gap on HFM morphology are evaluated. Elevated temperature (up to 350 °C) H2 permeances of 400 GPU with H2/CO2 selectivities > 20 are achieved. This unprecedented separation performance is a ground breaking achievement at temperatures traditionally considered out-of-reach for polymeric membranes. 相似文献
6.
《International Journal of Hydrogen Energy》2020,45(12):7444-7454
The incompatibility between nanofillers and polymer, caused by the agglomeration of nanoparticles and their weak interaction with each other, is still a challenge to develop mixed matrix composite membrane. Herein, we introduced the ZIF-8-TA nanoparticles synthesized by in situ hydrophilic modification into the hydrophilic poly(vinylamine) (PVAm) matrix to prepare composite membranes for H2 purification. The dispersion of ZIF-8 in water was improved by tannic acid modification, and the compatibility between ZIF-8 particles and PVAm matrix was enhanced by chemical crosslinking between the quinone groups in oxidized tannic acid (TA) and the amino groups in PVAm. Moreover, the compatibility between hydrophobic polydimethylsiloxane (PDMS) gutter layer and hydrophilic separation layer was achieved by the adhesion of TA-Fe3+ complex to the surface of PDMS layer during membrane preparation. The interlayer hydrophilic modification and the formation of separation layer were accomplished in one step, which simplified the preparation process. The experimental results indicated that when the TA addition used for modification was 0.5 g and the ZIF-8-TA0.5 content in membrane was 12 wt%, the prepared membrane showed the best separation performance with the CO2 permeance of 987 GPU and the CO2/H2 selectivity of 31, under the feed gas pressure of 0.12 MPa. 相似文献
7.
The development of compact hydrogen separator based on membrane technology is of key importance for hydrogen energy utilization, and the Pd-modified carbon membranes with enhanced hydrogen permeability were investigated in this work. The C/Al2O3 membranes were prepared by coating and carbonization of polyfurfuryl alcohol, then the palladium was introduced through impregnation–precipitation and colloid impregnation methods with a PdCl2/HCl solution and a Pd(OH)2 colloid as the palladium resources, and the reduction was carried out with a N2H4 solution. The resulting Pd/C/Al2O3 membranes were characterized by means of SEM, EDX, XRD, XPS and TEM, and their permeation performances were tested with H2, CO2, N2 and CH4 at 25 °C. Compared with the colloid impregnation method, the impregnation–precipitation is more effective in deposition of palladium clusters inside of the carbon layer, and this kind of Pd/C/Al2O3 membranes exhibits excellent hydrogen permeability and permselectivity. Best hydrogen permeance, 1.9 × 10−7 mol/m2 s Pa, is observed at Pd/C = 0.1 wt/wt, and the corresponding H2/N2, H2/CO2 and H2/CH4 permselectivities are 275, 15 and 317, respectively. 相似文献
8.
A thin amine-functionalized MIL-53 membrane with high permeability of hydrogen was successfully prepared on a porous α-Al2O3 support by using the secondary growth method. Seeded α-Al2O3 supports were prepared by a dip-coating technique. In contrast, a discontinuous membrane was obtained by using unseeded support under the same synthesis conditions, implying that the seeds play the key role in the formation of compact membranes. The resulting compact membranes were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM) and single gas permeation testing. Results showed that the thickness of the as-prepared membrane was around 2 ∼ 4 μm. Hydrogen permeance of the as-prepared membrane reached a remarkable value of 1.5 × 10−5 mol m−2 s−1·Pa−1 at room temperature under a 0.1 MPa pressure drop. The ideal H2/CO2 selectivity was found to be 4.4. In addition, the influence of seeding solution on the membrane performance was investigated. We found that the membrane permeance decreased and the ideal selectivity increased when the seeding solution content was increased. 相似文献
9.
Federico Guazzone Jacopo Catalano Ivan P. Mardilovich Jay Kniep Saurabh Pande Tony Wu Robert C. Lambrecht Subhash Datta Nikolaos K. Kazantzis Yi Hua Ma 《International Journal of Hydrogen Energy》2012
Three large scale (with each a permeable area of 200 cm2) highly structured composite Pd and Pd–Au membranes were prepared and tested in an actual stream of coal derived, but desulfurized, syngas at the National Carbon Capture Center (NCCC) in Wilsonville, Al. The objective of the study was to investigate the long term membrane stability and to establish the long term effects of syngas contaminants in the coal derived syngas other than sulfur compounds on H2 permeance and selectivity. The large scale membranes had thicknesses ranging from 7 to 14 μm, H2 permeances ranging from 20 to 28 Nm3 m−2 h−1 bar−0.5, and an undetectable He leak before the actual syngas test. In the syngas atmosphere, composite Pd and Pd–Au membranes showed an outstanding H2 permeance stability at 450 °C and 12.6 bar for approximately 200 h albeit a fast initial decline upon syngas introduction. The fast permeance decline observed at the introduction of the actual syngas was attributed to possible surface and/or bulk poisoning. An exceptionally high H2 purity level of 99.89% was achieved at 450 °C and 12.6 bar during the entire period of the measurement of over 200 h in syngas atmosphere representing a breakthrough result in the field never reported before with actual syngas from a coal gasification unit. 相似文献
10.
《International Journal of Hydrogen Energy》2019,44(60):32066-32079
A one-dimensional heterogeneous model for four configurations of a reactor, three micro-porous membrane reactors with O2 (O-MMTR), CO2 (C-MMTR) or H2O (H-MMTR) side-feeding strategy and one traditional reactor (i.e., multi-tubular fixed-bed reactor (MTR)), was developed to explain tri-reforming of methane to produce syngas. Effect of various side-feeding strategies on reactor performance containing CH4 and CO2 conversion, H2/CO ratio, and H2 yield was investigated under the same condition and then described by chemical species and temperature profiles. It was found that use of side-feeding strategies could be feasible, beneficial, and flexible in terms of change in membrane thickness and shell-side pressure for syngas production with H2/CO = 2 which is proper for methanol and Fischer-Tropsch process, and = 1.2 which is suitable for DME direct synthesis. However, the syngas produced by the MTR is only appropriate for the methanol and Fischer-Tropsch synthesis under the base case conditions. Also, the results show that the micro-porous membrane reactors have higher CO2 conversion, based on the H2/CO = 1.2; so these strategies are more environmentally friendly compared to the traditional reactor. 相似文献
11.
This paper reports a numerical study on the combustion and extinction characteristics of opposed-jet syngas diffusion flames. A model of one-dimensional counterflow syngas diffusion flames was constructed with constant strain rate formulations, which used detailed chemical kinetics and thermal and transport properties with flame radiation calculated by statistic narrowband radiation model. Detailed flame structures, species production rates and net reaction rates of key chemical reaction steps were analyzed. The effects of syngas compositions, dilution gases and pressures on the flame structures and extinction limits of H2/CO synthetic mixture flames were discussed. Results indicate the flame structures and flame extinction are impacted by the compositions of syngas mixture significantly. From H2-enriched syngas to CO-enriched syngas fuels, the dominant chain reactions are shifting from OH + H2→H + H2O for H2O production to OH + CO→H + CO2 for CO2 production through the key chain-branching reaction of H + O2→O + OH. Flame temperature increases with increasing hydrogen content and pressure, but the flame thickness is decreased with pressure. Besides, the study of the dilution effects from CO2, N2, and H2O, showed the maximum flame temperature is decreased the most with CO2 as the dilution gas, while CO-enriched syngas flames with H2O dilution has highest maximum flame temperature when extinction occurs due to the competitions of chemical effect and radiation effect. Finally, extinction limits were obtained with minimum hydrogen percentage as the index at different pressures, which provides a fundamental understanding of syngas combustion and applications. 相似文献
12.
Shin-Kun Ryi Jong-Soo Park Kyung-Ran HwangChun-Boo Lee Sung-Wook Lee 《International Journal of Hydrogen Energy》2013
This study investigates the module configuration for upscaling CO2 capture capacity to a bench-scale in hydrogen selective Pd-based composite membranes. In order to confirm effective upscaling, four plate-type membranes of two inch diameter were stacked in a newly designed plate-and-frame type module, reaching a total membrane surface area of 6.64 × 10−3 m2 (66.4 cm2). A pure gas test carried out using H2 and He confirmed that there were no effects of module configuration in gas permeation behavior, indicating that the upscale of the separation capacity by numbering-up of membranes using our module design was successful. The CO2 enrichment test was conducted using a 40%CO2 + 60%H2 mixture (i.e. a similar composition for the coal gasifier after both the shift reaction and H2O removal), under high feed pressure and flow rate, i.e. 600–2100 kPa and 0.48–0.72 N m3 h−1. The mixture gas test confirmed that the bench-scale membrane module could enrich 40% of the CO2 at a feed flow rate of 0.48 N m3 h−1 up to 93% with a hydrogen recovery ratio of >90% at 673 K and a total feed pressure of 2100 kPa, i.e. ∼4 times CO2 enrichment capacity of one membrane. 相似文献
13.
Lu Shao Shuai Quan Xi-Quan Cheng Xiao-Jing Chang Hong-Guang Sun Rong-Guo Wang 《International Journal of Hydrogen Energy》2013
In this study, a ‘green” method has been discovered by utilizing the amino functional poly(ethylene oxide) (PEO) and epoxy functional PEO with low molecular weights to synthesis cross-linked membranes for enhancing H2 purification and CO2 capture performance by retarding the crystallinity of semi-crystalline polymer of PEO. The cross-linking reaction can happen simply by mixing two materials without using any solvent. The reaction has been characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), solid-state 13C nuclear magnetic resonance (NMR) and the gel content test. Furthermore, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) confirm the amorphous structure of cross-linked PEO membranes, which should benefit the gas transport. The gas transport properties and the plasticizing phenomenon of CO2 have been examined in detail. Interestingly, the investigation on CO2 plasticization phenomenon reveals that the cross-linked PEO membrane should be plasticized immediately after the pressure load. The pressure dependence of CO2 permeability in the pressure range from 0.25 atm to 30 atm can be separated into two stages based on the permeability increment although the CO2 permeability continuously increases with the loading pressure. The gas transport results illustrate that CO2 has much larger permeability than that of any tested gas (including H2, N2 and CH4) attributing to the CO2-philic characteristic of ethylene oxide (EO) groups in the cross-linked PEO membrane. The good permeability and selectivity make the developed PEO membrane promising for H2 purification and CO2 capture applications. 相似文献
14.
Cu and Zn modified 13X zeolites prepared by ion exchange or impregnation and activated carbons (ACs) treated with KOH, NaOH or Na2CO3 solutions were studied as H2S sorbents for biogas purification for fuelling molten carbonate fuel cells. H2S sorption was studied in a new experimental set-up equipped with a high sensitivity potentiometric system for the analysis of H2S. Breakthrough curves were obtained at 40 °C with a fixed bed of 20 mg of the samples under a stream (6 L h−1) of 8 ppm H2S/He mixture. The adsorption properties of 13X zeolite improved with addition of Cu or Zn:Cu exchanged zeolite showed the best performances with a breakthrough time of 580 min at 0.5 ppm H2S, that is 12 times longer than the parent zeolite. In general, unmodified and modified ACs were more effective H2S sorbents than zeolites. Treating ACs with NaOH, KOH, or Na2CO3 solutions improved the H2S adsorption properties: AC treated with Na2CO3 was the most effective sorbent, showing a breakthrough time of 1222 min at 0.5 ppm, that is twice the time of the parent AC. 相似文献
15.
Changsong Cui Yue Wang Yongcheng Tong Shiwei Wang Chusheng Chen Zhongliang Zhan 《International Journal of Hydrogen Energy》2021,46(39):20305-20312
High temperature co-electrolysis of H2O/CO2 allows for clean production of syngas using renewable energy, and the novel fuel-assisted electrolysis can effectively reduce consumption of electricity. Here, we report on symmetric cells YSZ-LSCrF | YSZ | YSZ-LSCrF, impregnated with Ni-SDC catalysts, for CH4-assisted co-electrolysis of H2O/CO2. The required voltages to achieve an electrolysis current density of ?400 mA·cm?2 at 850 °C are 1.0 V for the conventional co-electrolysis and 0.3 V for the CH4-assisted co-electrolysis, indicative of a 70% reduction in the electricity consumption. For an inlet of H2O/CO2 (50/50 vol), syngas with a H2:CO ratio of ≈2 can be always produced from the cathode under different current densities. In contrast, the anode effluent strongly depends upon the electrolysis current density and the operating temperature, with syngas favorably produced under moderate current densities at higher temperatures. It is demonstrated that syngas with a H2:CO ratio of ≈2 can be produced from the anode at a formation rate of 6.5·mL min?1·cm?2 when operated at 850 °C with an electrolysis current density of ?450 mA·cm?2. 相似文献
16.
Ignition delays were measured in a shock tube for syngas mixtures with argon as diluent at equivalence ratios of 0.3, 1.0 and 1.5, pressures of 0.2, 1.0 and 2.0 MPa and temperatures from 870 to 1350 K. Results show that the influences of equivalence ratio on the ignition of syngas mixtures exhibit different tendency at different temperatures and pressures. At low pressure, the ignition delay increases with an increase in equivalence ratio at tested temperature. At high pressures, however, an opposite behavior is presented, that is, increasing equivalence ratio inhibits the ignition at high temperature and vice versa at intermediate temperature. The affecting degree of equivalence ratio on ignition delay is different for each mixture at given condition, especially for the syngas with high CO concentration. Sensitivity analyses demonstrate that reaction H + O2 = O + OH (R1) dominates the syngas oxidation under all conditions. With the increase of CO mole fraction, reactions CO + OH = CO2 + H (R27) and CO + HO2 = CO2 + OH (R29) become more important in the syngas ignition kinetics. With the increase of pressure, the reactions related to HO2 and H2O2 play the dominate role. The opposite influence of equivalence ratio on ignition delay at high- and intermediate-temperatures is chemically interpreted through kinetic analyses. 相似文献
17.
Attili Ramkiran Dai-Viet N. Vo Mohd Sabri Mahmud 《International Journal of Hydrogen Energy》2021,46(48):24845-24854
This paper reports about the production of syngas from dry reforming of ethanol (EDR) upon LaCuO3 and CeCuO3 catalysts that were prepared by using citrate sol-gel method. EDRs were run with fresh catalyst at each varied variable and 42 L/gcat/h of feed in a tubular reactor under atmospheric pressure. At equal feed pressure of reactants, steady state CO2 conversion increased exponentially from 700 to 800 °C while H2 and CO yields were increasing differently in sigmoid trend rendering H2/CO ratios to drop linearly from 1.7 to 1.0. However, these reaction results except the latter are otherwise when ethanol-CO2 ratio was increased (reducing CO2 pressure) at 750 °C. A minimum H2/CO ratio was evidenced at the ethanol-CO2 ratio of 1.48. LaCuO3 catalyst was more superior in producing syngas owing to its relatively low reduction temperature, high surface area and crystallinity, many active sites, good surface morphology and many C–O, C–H and hydroxyl groups. 相似文献
18.
《International Journal of Hydrogen Energy》2019,44(33):18505-18516
Demand for the clean and sustainable energy encourages the research and development in the efficient production and utilisation of syngas for low-carbon power and heating/cooling applications. However, diversity in the chemical composition of syngas, resulting due to its flexible production process and feedstock, often poses a significant challenge for the design and operation of an effective combustion system. To address this, the research presented in this paper is particularly focused on an in-depth understanding of the heat generation and emission formation of syngas/producer gas flames with an effect of the fuel compositions. The heat generated by flame not only depends on the flame temperature but also on the chemistry heat release of fuel and flame dimension. The study reports that the syngas/producer gas with a low H2:CO maximises the heat generation, nevertheless the higher emission rate of CO2 is inevitable. The generated heat flux at H2:CO = 3:1, 1:1, and 1:3 is found to be 222, 432 and 538 W m-2 respectively. At the same amount of heat generated, H2 concentration in fuel dominates the emission of NOx. The addition of CH4 into the syngas/producer gas with H2:CO = 1:1 also increases the heat generation significantly (e.g. 614 W m-2 at 20%) while decreases the emission formation. In contrast, adding 20% CO2 and N2 to the syngas/producer gas composition reduces the heat generation from 432 W m-2 to 364 and 290 W m-2, respectively. The role of CO2 on this aspect, which is weaker than N2, thus suggests CO2 is preferable than N2. Along with the study, the significant role of CO2 on the radiation of heat and the reduction of emission are examined. 相似文献
19.
Fast pyrolysis oil can be used as a feedstock for syngas production. This approach can have certain advantages over direct biomass gasification. Pilot scale tests were performed to investigate the route from biomass via fast pyrolysis and entrained flow gasification to syngas. Wheat straw and clean pine wood were used as feedstocks; both were converted into homogeneous pyrolysis oils with very similar properties using in-situ water removal. These pyrolysis oils were subsequently gasified in a pressurized, oxygen blown entrained flow gasifier using a thermal load of 0.4 MW. At a pressure of 0.4 MPa and a lambda value of 0.4, temperatures around 1250 °C were obtained. Syngas volume fractions of 46% CO, 30% H2 and 23% CO2 were obtained for both pyrolysis oils. 2% of CH4 remained in the product gas, along with 0.1% of both C2H2 and C2H4. Minor quantities of H2S (3 vs. 23) cm3 m−3, COS (22 vs. 94) cm3 m−3 and benzene (310 vs. 532) cm3 m−3 were measured for wood- and straw derived pyrolysis oils respectively. A continuous 2-day gasification run with wood derived pyrolysis oil demonstrated full steady state operation. The experimental results show that pyrolysis oils from different biomass feedstocks can be processed in the same gasifier, and issues with ash composition and melting behaviour of the feedstocks are avoided by applying fast pyrolysis pre-treatment. 相似文献
20.
The research compares the simulations of two chemical looping gasification (CLG) types using the ASPEN Plus simulation software for the production of H2. The simulated biomass type was poultry litter (PL). The first CLG type used in situ CO2 capture utilizing a CaO sorbent, coupled with steam utilization for tar reforming, allowing for the production of a CO2-rich stream for sequestration. Near-total sorbent recovery and recycle was achieved via the CO2 desorption process. The second type utilized iron-based oxygen carriers in reduction–oxidation cycles to achieve 99.8% Fe3O4 carrier recovery and higher syngas yields. Temperature and pressure sensitivity analyses were conducted on the main reactors to determine optimal operating conditions. The optimal temperatures ranged from 500 to 1250 °C depending on the simulation and reactor type. Atmospheric pressure proved optimal in all cases except for the reducer and oxidizer in the iron-based CLG type, which operated at high pressure. This CLG simulation generated the most syngas in absolute terms (2.54 versus 0.79 kmol/kmol PL), while the CO2 capture simulation generated much more H2-rich syngas (92.45 mol-% compared to 62.94 mol-% H2). 相似文献