The present invention relates in general to the catalytic conversion of hydrocarbons, and more particularly to the process for the catalytic hydrocracking of heavy hydrocarbon or petroleum feedstocks to midbarrel products using a catalyst comprising at least one of certain expanded clays. The process is efficient from the standpoints of conversion rates and selectivity for the desired middle distillates.
Catalytic midbarrel hydrocracking is a petroleum refining process of rapidly increasing importance due to the similarly rapid increase in the demand for middle-distillate fuels. In general the process comprises converting heavy hydrocarbon, e.g., petroleum, feedstocks boiling above about 700.degree. F. to lower-boiling products which boil in the range of about 300.degree. F. to about 700.degree. F., e.g., diesel and turbine fuels and furnace oils. The catalysts employed are of the dual functional type and comprise a hydrogenation-dehydrogenation component, such as a Group VIII noble metal or a combination of Group VIII and Group VIB metals, together with an acidic cracking component, such as silica-alumina or a zeolitic aluminosilicate.
Of the solid acid components, it is generally considered that zeolitic aluminosilicates are the most active in the sense that they convert the highest fraction of feedstock to products under reasonable operating conditions. Activity, however, is only one of three essential properties of a midbarrel hydrocracking catalyst--the other two properties being selectivity, i.e. the tendency of the catalyst to produce desirable products exclusively, and stability which is a measure of the useful operating life of the catalyst.
Battiste, et al. U.S. Pat. No. 4,637,991 discloses hydrocracking with a catalyst including a clay expanded with pillars derived from aluminum hydroxy chloride. Battiste also discloses a method for preparing a pillared interlayered clay admixed with zeolite. Vaughn U.S. Pat. No. 4,666,877 discloses expanded smectite clays in which the pillars are made up of aluminum and one or more transition metals. Such expanded clays are disclosed as being useful in petroleum hydrocracking catalysts. European Patent Publication No. 0,180,513A discloses a hydrocracking catalyst including a bridged smectite clay the layers of which are held apart by spacers composed of oxides of one or more of B, Mg, Al, P, Si, Ti, Cr, Zr, Mo and W; and an acidic stabilized Y-type zeolite. None of these references disclose rare earth elements as part of the propping agent for the clay, nor do these references disclose steaming the expanded clay to improve catalytic performance.