Partial catalytic oxidation of natural gas in synthesis gas

The possibility of rational utilization of associated petroleum gas in oil-producing regions is considered withrespect to small and medium-sized oil fields. It was shown that advanced technologies could provide additional benefits in terms ofsignificant expansion of the resource base of natural gas due to autonomous use of marginal oil fields as well as the fields with decliningproduction. The advantages of block supports with different structure, namely, cell, plate, tubular, mesh, fabric or foam materials, wereconsidered. Composite metal-oxide block catalysts were prepared using self-propagation high-temperature synthesis. Metal nickeldistributed in oxide matrix was used as an active component. Catalytic blocks with diameter of 1.0 cm and height of 1.5 cm were testedin the process of partial oxidation of natural gas. The natural gas/air ratio in the reaction mixture was 1 : 2.5 - 02.8 vol. The contact timewas 0.025 - 0.1 s during the process of partial oxidation of natural gas over Ni-containing catalysts. According to experimental resultson catalytic activity, the methane conversion and the catalyst productivity towards synthesis-gas were in dependence on the chemicaland phase composition of the catalysts prepared. The prepared catalysts were more productive in comparison with the systems havingplatinum group metals as an active component. The prepared catalytic blocks are characterized by low hydraulic resistance, stabilitytowards formation of carbon deposits, thermal shocks and large temperature gradients in the axial direction of the catalytic bed.According to the results obtained for catalyst samples before and after the catalytic experiment in conditions of natural gas conversionprocess it was shown that under the action of high-temperature reaction mixture the metal nickel in the block catalyst structure isdispersed for the second time, which leads to increase of the catalytic system activity during the process of natural gas conversion. Itwas established that each phase in the structure of the most effective multiphase catalyst (oxide or metal) provided realization of aspecial process. Combination of special processes led to the achievement of high productivity of catalyst. MgAl2O4 and MgO phaseswere able to dissolve nickel and transfer Ni particles along the surface of the catalytic block. These processes led to the formation of thehighly dispersed Ni particles. ZrO2 phase played the role of the structural promoter resisting to the aggregation of Ni nano-particles. Thepresence of tear-shaped Ni nano-particles increased the thermal conductivity and thermal stability of the catalytic blocks. It was shownthat the use of effective catalysts for partial oxidation of natural gas can significantly increase the performance of reactors as well asresult in lower capital and operating costs to produce synthesis gas in comparison with the processes currently used by the industry.

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