Research Of Catalysts On CO₂Hydrogenation To Light Olefins

With the rapid development of Chinese industry, the emissions of carbon dioxide increased year by year. The greenhouse effect caused by carbon dioxide imbalance, were concerned by scholars and scientific researchers from global chemical industry and environmental protection agency. It force people to find ways to resolve these problems.In recent years, due to the rapid development of Industry and large-scale exploitation of oil resources, ethylene and propylene as raw materials to synthesize polymer materials can not meet market demand. It got more attention to synthesize chemical products by develop new chemical technology but no-petroleum process. Many articles reported that dimethyl ether to ethylene by dehydration on catalyst surface and synthesis gas to light olefins, but seldom article related the hydrogenation of carbon dioxide to olefins.The chemical process of carbon dioxide hydrogenation to light olefins is not very complicated, because the subsequent separation system can be directly applied to the ethylene plant. It is necessary to get a highly active catalyst which can get a higher yield of light olefins and lower costs on the separation of product.In this thesis, The active carriers SiO2-ZrO2, SiO2and ZrO2prepared by coprecipitation from their nitrate. Then a certain amount of iron nitrate, copper nitrate, potassium nitrate, lanthanum nitrate were weighed and mixed into a solution, respectively dipped the active carriers into the solution by impregnation to obtain catalysts. Some effect factors to catalytic activity were researched, such as different carriers, the iron loadings of active component, the loadings of copper, lanthanum acting as additives, calcination temperature, the reduction temperature, reaction temperature, space velocity and so on. The structure and physicochemical properties of the catalysts were characterized by XRD, TPR-H2and TEM. It was discussed and preliminary assumed that the reaction mechanism of carbon dioxide hydrogen synthesis light olefins on the iron catalyst.The result indicates that when the SiO2-ZrO2play the role of vetor and in reaction system the ratio of hydrogen to carbon dioxide is three, if iron loadings in the catalyst is twenty percent, Fe:Cu:K:La is100:15:7:7, the calcination temperature is773K and the reduction temperature is723K,the Fe-Cu-K2O-La2O3catalyst will appear the high activity. At the reaction temperature is613K and space velocity is2400ml·h-1·g-1(cat), the catalysts show the strong catalytic active, if the reaction pressure is0.1Mpa.