Catalytic Cracking Of Atmospheric Residue With Ce/Zr Modified Iron Oxide Catalysts

Residual oil,which comes from the bottom of the distillation column,is one kind of typical heavy oil,It is characterized by its high viscosity,low H/C ratio and high content of metals and heteroatomic compounds.All of these makes it hard to process and utilize residual oil.One of the most efficient ways to turn residual oil into useful lighter hydrocarbons is hydrocracking,but it needs to be operated under high pressure and the use of hydrogen makes it a costly technology.Therefore,new approach needs to be develop to solve these problems.Steam catalytic cracking can be seen as the combination of catalytic cracking and hydrocracking,with steam serving as hydrogen source.The key to this process lies in the development of appropriate catalyst,which has better performance on decomposing macromolecules,generating active hydrogen and oxygen from steam and suppressing coke from formation.In this paper we developed two series of catalysts by coprecipitation of salt solutions,one is zirconia-supporting iron oxide,and the other is zirconia and ceria-supporting iron oxide.Inductively Coupled Plasma(ICP),X-ray Diffractometer(XRD),N2 adsorption and Raman spectroscopy were used to characterize the properties of catalysts.The experimental procedure was carried out on the fixed-bed flow reactor.It was found that both iron oxide supported with zirconia and that supported with zirconia and ceria showed better catalytic performance than iron oxide alone.Catalytic performance had much to do with the content of zirconia and ceria,and light oil yield reached the maximum of 43.7 wt.% and 47.9 wt.% for the two series of catalyst respectively.The influence of operating conditions such as temperature,W/F value and water to oil ratio on the yield of light was also studied.To achieve the highest light oil yield,the process was better carried out at 500 ?,with W/F value being 3.1 h and water to oil ratio being 3.Moreover,regenerability of the catalyst was investigated and the result demonstrated that although the catalytic activity decreased after the reaction,it remained at a high level after regeneration.