Development of catalysts with high activity and yield for hydrogen production by dry reforming of methane

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Thesis Type: Doctorate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, -, Turkey

Approval Date: 2014

Thesis Language: Turkish

Student: HÜSEYİN ARBAĞ

Supervisor: NAİL YAŞYERLİ

Open Archive Collection: AVESIS Open Access Collection

Abstract:

Dry reforming of methane is an important reaction because of converting two abundant gas, methane and carbon dioxide, to useful chemical products. In this study, activities of high surface area, nickel, nickel-cobalt, nickel-tungsten and nickel-magnesium incorporated alumina like mesoporous catalysts in dry reforming of methane were investigated. Mesoporous alumina materials synthesized by sol-gel and hydrothermal were used as a support of catalysts. Ni, Ni-Co, Ni-W and Ni-Mg metals were incorporated into the structure of catalysts by impregnation and one-pot synthesis method. Before catalytic activity tests, the catalysts were reduced in H2 gas flow. Physical and structural properties of catalysts were investigated by XRD, N2 adsorption-desorption, TPR, TPH, EDS, SEM, TEM and pyridine adsorbed FTIR analysis. In this study effects of reaction temperature (600oC and 700oC), reduction temperature (550oC, 750oC and 800oC) and ratio of reactants (CH4/CO2/Ar=1/1/1 and CH4/CO2=1/2) to activity of catalysts were investigated. Dry reforming methane reactions were carried out in a fixed-bed reactor system. 16Ni@SGA catalyst showed highest activity in catalytic tests carried out at 600oC, among the catalysts, 16Ni@MA, 16Ni-MA and 16Ni@SGA, which were reduced at 550oC in H2 gas and include 16% wt nickel. Activity of bimetallic 2.5Co-2.5Ni@SGA catalyst is higher than activity of monometallic 5Ni@SGA and TGA analysis after the reaction showed that carbon formation on the bimetallic catalyst is lower than monometallic catalyst. Incorporating W into the catalysts structure decreased the activity of catalyst, however, increased resistance of carbon formation. After the reaction tests carried out at 750oC for 4 hours, amount of coke on the surface of catalyst was decreased from 6% to %1 by incorporating W into the structure of catalysts. During the long time activity test carried out at 750oC for 150 hours, Ni-W catalysts showed high and stable activity. In this study, membrane reactor system was set up in order to increase H2 yield of catalysis. H2 yield of 5Ni-10W-MA catalysts can be increased by using membrane reactor system.