Abstract: Improved process and apparatus for purifying paraxylene from mixed C8-aromatic feedstocks are disclosed in which the use of at least two crystallization stages operated at different temperatures in combination with a final product separator improves purity and recovery while reducing capital and energy costs.

Abstract: A method and apparatus are disclosed for regenerating and/or stabilizing the activity of a dehydrogenation catalyst used in dehydrogenating an alkylaromatic hydrocarbon to obtain an alkenylaromatic hydrocarbon, the method comprising the steps of continuously or intermittently adding to a reactant stream an effective amount of an alkali metal or alkali metal compound without interrupting the dehydrogenation reaction.

Abstract: A method and associated apparatus for regenerating and/or stabilizing catalyst used in dehydrogenation of alkylaromatic hydrocarbons is disclosed. The alkylaromatic hydrocarbon (1) and steam (2) are combined to form feedstream (3) and pass into reactor (50). The ensuing product stream (4) is reheated in heater (52) to restore the heat lost and passed as partially converted reactant stream (5) into second reactor (54) and leaves as stream (6) comprising the dehydrogen product. Restoration and/or stabilization of catalyst is accomplished by an alkali metal compound which is fed into feedstream (2) and/or product stream (5) via supply means (46 and 66), respectively. The amount of alkali metal compound entering the reactor(s) is monitored by means (42 and 62) which may in turn be coupled to activating means (44 and 64) to signal and activate the supply means. This method and apparatus permit the restoration and/or stabilization of the catalyst to be performed without interrupting the dehydrogenation reaction.

Abstract: A method and apparatus are disclosed for regenerating and/or stabilizing the activity of a dehydrogenation catalyst used in dehydrogenating an alkylaromatic hydrocarbon to obtain an alkenylaromatic hydrocarbon, the method comprising the steps of continuously or intermittently adding to a reactant stream an effective amount of an alkali metal compound without interrupting the dehydrogenation reaction.

Abstract: A process is disclosed for pretreating a dilute ethylene feedstock with benzene, ethylbenzene, or mixtures thereof to reduce the higher olefin content of the ethylene feedstock and to render it suitable as the feed to an alkylation reactor for producing ethylbenzene. Benzene and ethylbenzene recovery are integrated with other downstream operations in the ethylbenzene production.

Abstract: A method and apparatus are disclosed for regenerating and/or stabilizing the activity of a dehydrogenation catalyst used in dehydrogenating an alkylaromatic hydrocarbon to obtain an alkenylaromatic hydrocarbon, the method comprising the steps of continuously or intermittently adding to a reactant stream an effective amount of an alkali metal compound without interrupting the dehydrogenation reaction.