Breakthrough in the field of coal chemistry
Recently, the research team led by Prof. Xinhe Bao, an academician of the Chinese Academy of Sciences, and Prof. Xiulian Pan at the Dalian Institute of Chemical Physics (DICP), developed a nanocomposite, which catalyzes direct conversion of synthesis gas to light olefins. The work was just published at Science on March 4 (http://dx.doi.org/10.1126/science.aaf1835). Chinese Patent applications and PCT are pending. Prof. de Jong from Utrecht University commented in his Perspective, which was published in the same issue of Science(http://dx.doi.org/10.1126/science.aaf3250), that the research reported by Jiao et al. should be of interest to both academia and industry and that the new process could become a serious competitor for industrial processes such as FTO and MTO. FTO represents process of Fischer-Tropsch to olefins and MTO Methanol to olefins.
Fischer-Tropsch synthesis (FTS) is a well known process catalyzed by metal-based catalysts, converting synthesis gas (a mixture of CO and H2) into hydrocarbons. It was invented more than 90 years ago and is still in industrial practice to date for producing synthetic lubricants and synthetic fuels. The process involves CO and H2 activation over metal surfaces, forming CHx mononer. These mononers go through surface polymerization leading to formation of a wide range of hydrocarbons with different chain lengths. As a result, the selectivity to C2–C4 hydrocarbons, including paraffins and olefinscontaining 2 to 4 carbon atoms, will not exceed 58%.
Now, the researchers at DICP developed a composite catalystaffording two types of active sites with complementary properties. The partially reducedoxide surface (ZnCrOx) activates CO and H2, and C−C coupling is subsequentlymanipulated within the confined acidic pores of zeolites. Thus, the surface polymerization of CHx was circumvented. This leads to a high selectivity of light olefins (80%) and light hydrocarbons C2–C4 (94%) at carbon monoxide (CO) conversion of 17%. Furthermore, in this new process, the surface oxygen from dissociated CO is removed by reacting with CO forming CO2.Itmay allowuse of coal- and biomass-derived syngas with a low H2/CO ratioand thus there is no necessity for WGS, which could reduce both water and energy-consumption.These findings open up a new avenue for development of not only syngas-to-olefin technology but also other processes.
The work is supported by the National Natural Science Foundation of China, the Ministry of Science and Technology and“Strategic Priority Research Program” of the Chinese Academy of Sciences.