Abstract: An improved catalytic reforming process. The process is operated at high severity in order to obtain a reformate product having an enhanced octane rating. Higher octane reformate is required to compensate for the reduction or total elimination of lead-based additives used in motor gasoline for increasing octane rating, since reformate is a primary component of motor gasoline. High severity operation results in the formation of quantities of polycyclic aromatic compounds whose presence is highly undesirable. These compounds are removed from the vaporous products of the catalytic reforming process by adsorption on an appropriate material. It was totally unexpected to find that these very high molecular weight compounds are present in vapor streams comprised of hydrogen and light normally-gaseous hydrocarbons such as methane, ethane, and propane.

Abstract: Methods of starting up and shutting down reactors used in hydrocracking and hydrodesulfurization of black oils. The reactor is flushed with a heavy vacuum gas oil between the circulation of the black oil feed stream and the lighter hydrocarbon stream used during the low temperature portion of the operations.