Treatment of hydrocarbon streams, and in one non-limiting embodiment refinery distillates, with high pH aqueous reducing agents, such as borohydride, results in reduction of the sulfur compounds such as disulfides, mercaptans and thioethers that are present to give easily removed sulfides. The treatment converts the original sulfur compounds into hydrogen sulfide or low molecular weight mercaptans that can be extracted from the distillate with caustic solutions, hydrogen sulfide or mercaptan scavengers, solid absorbents such as clay or activated carbon or liquid absorbents such as amine-aldehyde condensates and/or aqueous aldehydes.

The invention concerns a process for the production of butadiene from an ethanol feed comprising at least 80% by weight of ethanol, comprising at least one step A) for the conversion of ethanol into acetaldehyde A), a step B) for converting an ethanol/acetaldehyde mixture into butadiene, a step C1) for hydrogen treatment, a step D1) for butadiene extraction, a first butadiene purification step D2), a subsequent butadiene purification step D3), an effluent treatment step E1), a step E2) for eliminating impurities and brown oils and a step F) for scrubbing with water.

The invention concerns a process for the production of butadiene from an ethanol feed comprising at least 80% by weight of ethanol, comprising at least one step A) for the conversion of ethanol into acetaldehyde A), a step B) for converting an ethanol/acetaldehyde mixture into butadiene, a step C1) for hydrogen treatment, a step D1) for butadiene extraction, a first butadiene purification step D2), a subsequent butadiene purification step D3), an effluent treatment step E1), a step E2) for eliminating impurities and brown oils and a step F) for scrubbing with water.

A process for producing paraxylene is provided. The process includes separating a first mixture of C.sub.8 aromatic hydrocarbons in a simulated moving bed apparatus using a desorbent to produce (i) an extract comprising ≧50.0 wt % of the paraxylene in the first mixture; (ii) a desorbent-rich raffinate comprising ≧75 wt % of the desorbent withdrawn, and (iii) an desorbent-lean raffinate comprising ≦25 wt % of the desorbent withdrawn in the desorbent-rich and desorbent-lean raffinates. The desorbent-lean raffinate can then, without an intervening separation step, be passed to a refinery process or a vapor phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-lean raffinate. The desorbent-rich raffinate can be passed to a liquid phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-rich raffinate.

A process for producing paraxylene is provided. The process includes separating a first mixture of C.sub.8 aromatic hydrocarbons in a simulated moving bed apparatus using a desorbent to produce (i) an extract comprising ≧50.0 wt % of the paraxylene in the first mixture; (ii) a desorbent-rich raffinate comprising ≧75 wt % of the desorbent withdrawn, and (iii) an desorbent-lean raffinate comprising ≦25 wt % of the desorbent withdrawn in the desorbent-rich and desorbent-lean raffinates. The desorbent-lean raffinate can then, without an intervening separation step, be passed to a refinery process or a vapor phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-lean raffinate. The desorbent-rich raffinate can be passed to a liquid phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-rich raffinate.

A process for the isomerization of a feed of hydrocarbon compounds containing C.sub.5 and/or C hydrocarbon compounds, comprising: a) supplying an isomerization unit with at least one liquid fraction of the feed of hydrocarbon compounds and isomerizing the feed in the presence of a chlorinated catalyst; b) supplying a stabilization unit containing at least one stabilization column with the effluent obtained from the isomerization unit and separating the effluent; c) providing an absorption unit having one absorption column; d) extracting a liquid flow enriched in chlorinated compounds from the absorption unit which is recycled to the isomerization unit; and e) extracting the liquid flow containing at least one isomerate from the stabilization unit.

A process for the isomerization of a feed of hydrocarbon compounds containing C.sub.5 and/or C hydrocarbon compounds, comprising: a) supplying an isomerization unit with at least one liquid fraction of the feed of hydrocarbon compounds and isomerizing the feed in the presence of a chlorinated catalyst; b) supplying a stabilization unit containing at least one stabilization column with the effluent obtained from the isomerization unit and separating the effluent; c) providing an absorption unit having one absorption column; d) extracting a liquid flow enriched in chlorinated compounds from the absorption unit which is recycled to the isomerization unit; and e) extracting the liquid flow containing at least one isomerate from the stabilization unit.

A process for the isomerization of a feed of hydrocarbon compounds containing C.sub.5 and/or C hydrocarbon compounds, comprising: a) supplying an isomerization unit with at least one liquid fraction of the feed of hydrocarbon compounds and isomerizing the feed in the presence of a chlorinated catalyst; b) supplying a stabilization unit containing at least one stabilization column with the effluent obtained from the isomerization unit and separating the effluent; c) providing an absorption unit having one absorption column; d) extracting a liquid flow enriched in chlorinated compounds from the absorption unit which is recycled to the isomerization unit; and e) extracting the liquid flow containing at least one isomerate from the stabilization unit.

A demethanizer employing C3, C4 and C4+ hydrocarbons as absorbents can be employed in a methanol to olefin process to reduce both operating and capital costs in comparison to a convention process which employs only cryogenic distillation to remove methane and other low boilers from a light olefin process stream. By reducing the use of propane, the size and operating costs of the C3 splitter can be reduced thereby providing an economic advantage over conventional applications.

A demethanizer employing C3, C4 and C4+ hydrocarbons as absorbents can be employed in a methanol to olefin process to reduce both operating and capital costs in comparison to a convention process which employs only cryogenic distillation to remove methane and other low boilers from a light olefin process stream. By reducing the use of propane, the size and operating costs of the C3 splitter can be reduced thereby providing an economic advantage over conventional applications.