Patent ID: 11970666
Assignee: NESTE OYJ
Field: Basic materials chemistry (Chemistry)
Classification: CPC C  Y | IPC C

Claim 0:
1. A process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having a nitrogen impurity of 10 wppm or more, measured as elemental nitrogen, the process comprising:
introducing a hydrotreatment entry stream containing the oxygenated hydrocarbon feedstock, a hydrogen-rich gas, and optionally a product recycle diluting agent, to a second catalytic zone of a hydrotreatment reactor having a first catalytic zone arranged above the second catalytic zone, the hydrotreatment entry stream being introduced at an inlet between the first and the second catalytic zones;
mixing the hydrotreatment entry stream with part of a first hydrotreated effluent from the first catalytic zone, wherein said part of said first hydrotreated effluent includes liquid hydrocarbons with dissolved hydrogen, where the second catalytic zone is operated at a first temperature and a first pressure causing at least hydrodeoxygenation and hydrodenitrification to an extent where a second hydrotreated effluent from the second catalytic zone of the hydrotreatment reactor contains mainly hydrocarbons, and wherein the oxygenated hydrocarbon feedstock has been converted to ≥95% hydrocarbons,
subjecting the second hydrotreated effluent from the second catalytic zone of the hydrotreatment reactor to a first separation stage where at least part of the second hydrotreated effluent is separated into a first gaseous fraction and a first hydrotreated liquid, where the first hydrotreated liquid contains ≥95 wt % hydrocarbons and >1 wppm nitrogen;
introducing at least part of the first hydrotreated liquid and the hydrogen-rich gas in the hydrotreatment reactor to the first catalytic zone, at a first inlet temperature that is higher than a second inlet temperature in the second catalyst zone of the hydrotreatment reactor and at a second pressure causing hydrodeoxygenation and hydrodenitrification;
removing a product side stream containing part of the first hydrotreated effluent from the first catalytic zone between the first and second catalytic zones, the product side stream containing a liquid component and a gaseous component, where the liquid component of the side stream contains ≥99 wt % hydrocarbons and ≤1 wppm nitrogen, measured as elemental nitrogen;
optionally isomerising the product side stream in an isomerisation reactor including at least one catalytic zone, in which the product side stream and a hydrogen-rich gas containing ≤1 ppm (mol/mol) nitrogen, measured as elemental nitrogen, are introduced into the at least one catalytic zone of the isomerization reactor at a third inlet temperature and a third pressure causing at least hydroisomerisation to produce a first isomerised effluent; and
subjecting the first isomerised effluent from the isomerisation reactor to a second separation stage, where the first isomerised effluent is separated into a second gaseous fraction and a first isomerised liquid, where the first isomerised liquid contains ≥30 wt % branched hydrocarbons, and/or an increase in branched hydrocarbons of ≥30 wt % compared to the product side stream,
wherein part of the first hydrotreated effluent from the first catalytic zone heats the hydrotreatment entry stream,
wherein the second inlet temperature and the first pressure of the second catalyst zone is 200-400° C. and 10-150 bar, respectively, and
wherein the first inlet temperature and the second pressure of the first catalyst zone is 250-450° C. and 10-150 bar, respectively.