One-step conversion of syngas to light olefins over bifunctional metal-zeolite catalyst

Light olefins (C2-C4) are fundamental building blocks for the manufacture of polymers,chemical intermediates,and solvents.In this work,we realized a composite catalyst,comprising MnxZry oxides and SAPO-34 zeolite,which can convert syngas (CO + H2) into light olefins.MnxZry oxide catalysts with different Mn/Zr molar ratios were facilely prepared using the coprecipitation method prior to physical mixing with SAPO-34 zeolite.The redox properties,surface morphology,electronic state,crystal structure,and chemical elemental composition of the catalysts were examined using H2-TPR,SEM,XPS,XRD,and EDS techniques,respectively.Tandem reactions involved activation of CO and subsequent hydrogenation over the metal oxide catalyst,producing methanol and dimethyl ether as the main reaction intermediates,which then migrated onto SAPO-34 zeolite for light olefins synthesis.Effects of temperature,pressure and reactant gas flow rate on CO conversion and light olefins selectiv-ity were investigated in detail.The Mn1Zr2/SAPO-34 catalyst (Mn/Zr ratio of 1∶2) attained a CO conversion of 10.8％ and light olefins selectivity of 60.7％,at an optimized temperature,pressure and GHSV of 380 ℃,3 MPa and 3000 h-1 respectively.These findings open avenues to exploit other metal oxides with CO activation capa-bilities for a more efficient syngas conversion and product selectivity.