US 5,292,987 AGranted

Hydrocarbon adsorption and isomerization process

AssigneeUop LLC

InventorsAndrew S. Zarchy, Nelson Cusher, Gary J. Welch

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Abstract

Processes are disclosed for the adsorption and isomerization of paraffinic hydrocarbons wherein an absorption cycle is employed that utilizes a non-adsorbable purge gas for regenerating the adsorber beds, which cycle includes adsorption, regeneration and void space purging steps and wherein one of said void space purging steps comprises passing an adsorber feed to the adsorber bed to purge non-adsorbable purge gas from the void space and said step is continued until at least a portion of the non-adsorbed hydrocarbons in the adsorber feed elutes from the void space of the adsorber bed. Processes are further disclosed for sulfur and/or ammonia-containing feeds that employ additional conversion and adsorption zones to prevent the sulfur and/or ammonia compounds from contacting the isomerization catalyst. The products from the processes are useful as motor fuel blending components.

Claims18

Dependent claims

An adsorption-isomerization process for increasing the dimethyl-branched paraffin content of a hydrocarbon feed containing reactant components selected from the group consisting of normal paraffins or monomethyl-branched paraffins in the C.sub.5 -C.sub.6 carbon range or mixtures thereof, said process comprising the steps of:

(a) passing a reactor feed comprising hydrogen and said reactant components to an isomerization reactor to produce a reactor effluent comprising dimethyl-branched paraffins and an adsorbate fraction comprising said reactant components;
(b) passing a portion of an adsorber feed comprising at least a portion of said reactor effluent as a first feedstream to a first adsorber bed in an adsorption zone comprising at least four adsorber beds containing adsorbent and bed void space to adsorb said adsorbate fraction and withdrawing an adsorption effluent comprising said dimethyl-branched paraffins from said first adsorber bed;
(c) passing a first purge feed comprising a hydrogen-containing non-adsorbable purge gas to said first adsorber bed wherein the void space contains a first void space gas comprising said reactant components and dimethyl-branched paraffins, withdrawing a first purge effluent comprising said first void space gas from said first adsorber bed and passing said first purge effluent to at least one other of said adsorber beds to comprise a portion of said adsorber feed;
(d) passing a second purge feed comprising said hydrogen-containing non-adsorbable purge gas and a portion of said dimethyl-branched paraffins to said first adsorber bed to desorb said adsorbate fraction and withdrawing a desorption effluent comprising said hydrogen-containing purge gas, at least a portion of said dimethyl-branched paraffins, and said adsorbate fraction from said first adsorber bed;
(e) passing a second feedstream comprising a portion of said adsorber feed to said first adsorber bed wherein the void space contains a second void space gas comprising said non-adsorbable purge gas from said first adsorber bed, withdrawing a second purge effluent comprising said second void space gas from said first adsorber bed, passing said second purge effluent to at least one other of the adsorber beds to comprise a portion of said hydrogen-containing purge gas, and continuing said passing of said second purge effluent until a portion of said dimethyl-branched paraffins has eluted from the void space of said first adsorber bed such that the concentration of said hydrogen-containing purge gas in said second purge effluent is less than 90 mol. %;
and
(f) passing at least a portion of said desorption effluent to the isomerization reactor to comprise at least a portion of said reactor feed.

4 more elements

An adsorption-isomerization process for increasing the dimethyl-branched paraffin content of a hydrocarbon feed containing components selected from the group consisting of normal paraffins or monomethyl-branched paraffins in the C.sub.5 -C.sub.6 carbon range or mixtures thereof, which feed additionally contains at least sulfur and/or nitrogen components, said process comprising:

(a) passing said hydrocarbon feed to a catalytic reaction zone containing a catalytically effective amount of catalyst, under hydrogen sulfide and ammonia forming conditions to convert substantially all of the sulfur in the hydrocarbon feed to hydrogen sulfide and substantially all of the nitrogen in the hydrocarbon feed to ammonia and thereby produce a hydrogen sulfide and/or ammonia containing hydrocarbon feed;
(b) passing said hydrogen sulfide and/or ammonia-containing hydrocarbon feed to a first adsorber bed in a first adsorption zone having at least two adsorber beds containing adsorbent selective for the adsorption of hydrogen sulfide and ammonia to adsorb said hydrogen sulfide and/or ammonia and withdrawing a first adsorption effluent depleted in said hydrogen sulfide and/or ammonia;
(c) passing a reactor feed comprising hydrogen and at least a portion of said first adsorption effluent to an isomerization reactor containing an isomerization catalyst which is deleteriously affected by the presence of hydrogen sulfide and/or ammonia to produce a reactor effluent comprising said dimethyl-branched paraffins and an adsorbate fraction comprising said components;
(d) passing a portion of an adsorber feed comprising at least a portion of said reactor effluent as a first feedstream to one adsorber bed in a second adsorption zone having at least four adsorber beds containing adsorbent and bed void space to adsorb said adsorbate fraction and withdrawing a second zone adsorption effluent comprising said dimethyl-branched paraffins;
(e) passing a first purge feed comprising a hydrogen-containing non-adsorbable purge gas to the one adsorber bed in the second adsorption zone wherein the void space contains a first void space gas comprising said reactant components and dimethyl-branched paraffins, withdrawing a first purge effluent comprising said first void space gas and passing said first purge effluent to at least one other adsorber bed in the second adsorption zone to comprise a portion of said adsorber feed;
(f) passing a second purge feed comprising said hydrogen-containing non-adsorbable purge gas and a portion of said dimethyl-branched paraffins to the one adsorber bed in the second adsorption zone to desorb said adsorbate fraction and withdrawing a second zone desorption effluent comprising said hydrogen-containing non-adsorbable purge gas, said adsorbate fraction, and at least a portion of dimethyl-branched paraffins;
(g) passing a second feedstream comprising a portion of said adsorber feed to the one adsorber bed in the second adsorption zone wherein the void space contains a second void space gas comprising said non-adsorbable purge gas, withdrawing a second purge effluent comprising said second void space gas, passing said second purge effluent to at least one other adsorber bed in the second adsorption zone to comprise a portion of said hydrogen-containing non-adsorbable purge gas and continuing said passing of said second purge effluent until a portion of said dimethyl-branched paraffins has eluted from the void space of the one adsorber bed in the second adsorption zone until the concentration of the hydrogen in said second purge effluent is less than 90 mol. %;
(h) passing said second zone desorption effluent to the isomerization reactor to comprise at least a portion of said reactor feed;
and
(i) passing at least a portion of said second zone adsorption effluent without recovering said hydrogen-containing, non-adsorbable purge gas to said first adsorber bed to desorb said hydrogen sulfide and/or ammonia and provide a first zone desorption effluent comprising said dimethyl-branched paraffins and hydrogen sulfide and/or ammonia.

7 more elements

Dependencies are inferred from the claim text.