The Impact Of Pore-expanding Modified Sorption Complex Catalyst On Hydrogen Production In ReSER Process

Reactive sorption enhanced reforming(ReSER) is a new technology for hydrogen production by the principle of in site CO2 capture to enhanced the reforming reaction equilibrium towards the direction of producing hydrogen, and reach the target of lower reaction temperature, less CO2 emission and less energy consumption for hydrogen production. ReSER process is significant for the energy industry, chemical industry, refinery industry, aerospace industry and so on. The current research found that the carbon space velocity of reforming reaction of a sorption complex catalyst is not satisfied with the industry requirement. It means that the increase the reactive activity of the sorption complex catalyst is one of the urgent problems to be solved for the ReSER industrial application.The researches concerned the modified of sorption complex catalyst's microstructure and CO2 sorption performance by preparation and addition of the pore-expanding agents. Sorption complex catalyst's activity used in ReSER process of hydrogen production were tested in a fixed bed reactor. As the basic research of the sorption complex catalyst, the CaO content effect on the microstructure and CO2 sorption performance of a CaO-Al2O3 support were also be studied.Experiemtal studies firstly concerns on the preparation of sorption complex catalyst by adding ammonium aluminum carbonate, polyglycol, active carbon, nano-carbon and cetyltrimethylammonium bromide hydroxide as pore-expanding agents. Pore structure and specific surface area were characterized by BET(Brunauer-Emmett-Teller) test. The results show that adding pore-expanding agent could enlarger pore size of the sorption complex catalyst. Compared with the unmodified sorption complex catalyst, most of the modified catalyst increase 2-3 times specific surface area. When CaO content increase, The pore size become larger, the specific surface area becomes smaller.The sorption capacity, sorption rate and CaCO3 decomposition temperature of sorption complex catalyst and CaO-Al2O3 support was characterized by thermo-gravity analyzer(TGA). Results show that after pore structure modified by PEG 6000, the CO2 sorption capacity increase by 44%, the CO2 sorption rate become faster and the decomposition temperature of CaCO3 decrease by 76℃. When CaO content increased, the CO2 sorption rate of CaO-Al2O3 become faster and the CO2 sorption capacity of CaO-Al2O3 support has a nonlinear increasing. The results also show that pure CaO has lower CO2 sorption rate than that of CaO-Al2O3 support with CaO content of 69% and 83%.The crystal type of the sorption complex catalyst were characterized by X-ray diffraction(XRD) and the reduction performance of the sorption complex catalyst were characterized by temperature programmed reduction(TPR). The results show that complex catalyst which has improved pore size and higher specific surface area has higher dispersion of NiO. High specific surface area make smaller crystal size of NiO and suppress NiAl2O4 generation. It suppressγ-Al2O3 generation in CaO-Al2O3 by increase CaO content. There was noγ-Al2O3 to be detected in CaO-Al2O3 support when CaO content is more than 27%.The ReSER process of hydrogen production was evaluated on a laboratory scale fix bed reactor system. Under the reaction conditions of reaction temperature of 600℃, reaction pressure of 0.lMPa and H2O/CH4 mole ratio of 4, H2 content (on dry basis) 94.2% was produced and the corresponding CH4 conversion was 86.0% of pore structure modified sorption complex catalyst under a carbon space velocity of 1700h-1, compared to H2content (on dry basis) 81.1% and CH4 conversion 53.1% that of unmodified sorption complex catalyst under a carbon space velocity of 1020h-1.The results of this study show that pore-expanding agent improve the pore structure and improve activity of sorption complex catalyst in ReSER process. The CaO content is greater impact on pore structure and sorption performance. The results had an significant on the guidance of the improvement of further development of catalyst used in ReSER process.