Multi-bed hydrodewaxing process

Claim 2

A continuous cascading multi-bed process for catalytic hydrodewaxing of waxy, heavy hydrocarbon fraction feedstock comprising the conversion steps of partially dewaxing the feedstock by contacting the feedstock at elevated temperature with a first catalyst bed comprising a ZSM-5 type crystalline zeolite in the presence of hydrogen; subsequently contacting the partially dewaxed effluent from the first bed with at least one separate hydrogenation catalyst bed under hydrotreating conditions to saturate olefinic reaction products of the dewaxing step; further catalytically dewaxing the hydrotreated feedstock in contact with ZSM-5 type catalyst in at least one additional catalytic dewaxing step; and further hydrogenating the dewaxed feedstock in an additional hydrotreating step.

Claim 3

The process of claim 1 wherein the feedstock consists essentially of a lubricant range petroleum fraction and the dewaxing catalysts consist essentially of acid nickel ZSM-5.

Claim 4

The process of claim 2 wherein the hydrogenation catalyst comprises at least one Group VIII metal.

Claim 5

The process of claim 3 wherein the hydrogenation catalyst comprises palladium on an inert support.

Claim 6

The process of claim 1 wherein all of the conversion steps are conducted in a reactor shell having alternating operatively-connected fixed beds of hydrodewaxing zeolite catalyst and hydrogenation catalyst.

Claim 7

The process of claim 5 wherein quenching hydrogen is introduced to cascaded effluent from the dewaxing steps prior to hydrotreating, thereby cooling the cascaded dewaxing effluent to hydrotreating temperature.

Claim 8

A continuous cascading multi-bed process for catalytic hydrodewaxing of waxy petroleum feedstock in a reactor shell having alternating operatively-connected beds of hydrodewaxing zeolite catalyst and hydrogenation catalyst; comprising the conversion steps of (a) partially dewaxing the feedstock by contacting the feedstock at elevated temperature wlth a first medium pore crystalline zeolite catalyst bed in the presence of hydrogen; (b) cooling and subsequently contacting the partially dewaxed effluent from step (a) with at least one separate hydrogenation catalyst bed under hydrotreating conditions; (c) further dewaxing the hydrotreated feedstock from step (b) in at least one additional catalytic dewaxing step whereby catalyst aging is substantially decreased; and (d) further hydrogenating the dewaxed feedstock from step (c) in an additional hydrotreating step.

Claim 9

A continuous cascading multi-bed process for catalytic hydrodewaxing of waxy petroleum feedstock in a reactor shell having alternating operatively-connected beds of hydrodewaxing zeolite catalyst and hydrogenation catalyst; comprising the conversion steps of (a) partially dewaxing the feedstock by contacting the feedstock at elevated temperature wlth a first medium pore crystalline zeolite catalyst bed in the presence of hydrogen; (b) cooling and subsequently contacting the partially dewaxed effluent from step (a) with at least one separate hydrogenation catalyst bed under hydrotreating conditions; (c) further dewaxing the hydrotreated feedstock from step (b) in at least one additional catalytic dewaxing step whereby catalyst aging is substantially decreased; and (d) further hydrogenating the dewaxed feedstock from step (c) in an additional hydrotreating step.

Claim 10

The process of claim 7 wherein quenching hydrogen is introduced to cascaded effluent from steps (a) and (c) prior to hydrotreating, thereby cooling the cascaded dewaxing effluent to hydrotreating temperature.

Claim 11

The process of claim 7 wherein the zeolite catalyst comprises a pentasil aluminosilicate and the hydrogenation catalyst comprises a Group VIII metal.

Claim 12

The process of claim 9 wherein the zeolite catalyst consists essentially of a ZSM-5 type zeolite and the hydrogenation catalyst comprises Pd.

Claim 13

The process of claim 9 wherein at least two hydrodewaxing zones are serially connected to intermediate and final hydrotreating zones, and wherein reaction temperature is adjusted between adjacent zones by direct or indirect contact with a heat exchange medium.

Claim 14

The process of claim 7 wherein steps (a) and (c) are conducted under dewaxing conditions at about 250° to 400° C.