Abstract: The economics of a catalytic process using a fluidized conversion zone and a relatively expensive catalyst for converting an oxygenate to light olefins are substantially improved by recovering and recycling effluent contaminating catalyst particles from the product effluent stream withdrawn from the conversion zone which are present despite the use of one or more vapor-solid cyclone separating means to clean up this effluent stream. The contaminating catalyst particles are separated from this product effluent stream using a wet scrubbing zone and an optional dewatering zone to recover a slurry containing the contaminated particles which, quite surprisingly, can be successfully directly recycled to the oxygenate conversion zone or to the associated catalyst regeneration zone without loss of any substantial amount of catalytic activity thereby decreasing the amount of fresh catalyst addition required to make up for this source of catalyst loss.

Abstract: A catalytic hydrocracking process wherein a hydrocarbonaceous feedstock and a liquid recycle stream is contacted with hydrogen in a hydrocracking reaction zone at elevated temperature and pressure to obtain conversion to lower boiling hydrocarbons. A liquid hydrocarbonaceous stream produced from the effluent of the hydrocracking reaction zone is fractionated in a first zone of a divided-wall fractionation zone to produce at least one liquid hydrocarbonaceous product stream and a liquid hydrocarbonaceous stream containing hydrocarbons boiling at a temperature in the boiling range of the feedstock and heavy polynuclear aromatic compounds. At least a portion of the liquid hydrocarbonaceous stream containing heavy polynuclear aromatic compounds is introduced into a second zone of the divided-wall fractionation zone to produce a stream rich in polynuclear aromatic compounds.

Abstract: A hydrocracking process wherein the undesirable production of polynuclear aromatic compounds is controlled by removing a small dragstream of high pressure product stripper bottoms to reject polynuclear aromatic compounds and recovering valuable diesel boiling range hydrocarbons and unconverted feedstock by routing the dragstream to a hot flash separator and subsequently to a divided wall fractionation zone to produce a concentrated stream of polynuclear aromatic compounds while recovering the valuable hydrocarbon compounds.

Abstract: A catalytic hydrocracking process wherein a hydrocarbonaceous feedstock and a liquid recycle stream is contacted with hydrogen in a hydrocracking reaction zone at elevated temperature and pressure to obtain conversion to lower boiling hydrocarbons. A liquid hydrocarbonaceous stream produced from the effluent of the hydrocracking reaction zone is fractionated in a first zone of a divided-wall fractionation zone to produce at least one liquid hydrocarbonaceous product stream and a liquid hydrocarbonaceous stream containing hydrocarbons boiling at a temperature in the boiling range of the feedstock and heavy polynuclear aromatic compounds. At least a portion of the liquid hydrocarbonaceous stream containing heavy polynuclear aromatic compounds is introduced into a second zone of the divided-wall fractionation zone to produce a stream rich in polynuclear aromatic compounds.

Abstract: A process for separating two close-boiling chemical compounds by fractionation wherein the bottoms liquid stream removed from the fractionation column is flashed to produce cool liquid which is then used to condense overhead vapors of the column. The column is reboiled by vapor derived from the flashed bottoms liquid stream and which has been heated by compression in a heat pump.