Method of converting feeds from renewable sources in co-processing with a petroleum feed using a catalyst based on nickel and molybdenum

Abstract

The invention relates to a method of hydrotreatment in co-processing of petroleum feeds, in a mixture with at least one feed obtained from renewable sources, for producing fuel bases (kerosene and / or gas oil) having a sulphur content below 10 ppm, said method comprising the following stages:a) a first hydrotreatment stage in which said feed passes through at least one first fixed-bed catalytic zone comprising at least one bulk or supported catalyst comprising an active phase constituted by at least one group VIB element and at least one group VIII element, said elements being in the form of sulphide and the atomic ratio of the group VIII metal (or metals) to group VIB metal (or metals) being strictly greater than 0 and less than 0.095,b) a second hydrotreatment stage into which the effluent from the first hydrotreatment stage is sent directly, and in which said effluent passes through at least one second fixed-bed catalytic zone comprising at least one hydrotreatment catalyst.

Description

[0001]The present invention relates to a method of hydrotreatment of a feed constituted by a mixture of feeds obtained from renewable sources and in particular oils of vegetable or animal origin, combined with petroleum cuts with the aim of producing gas oil fuel bases.[0002]It relates to a method enabling the required environmental specifications to be met, for example for an atmospheric gas oil obtained by direct distillation of a crude oil, in a mixture with a feed obtained from a renewable source, in order to produce gas oil and / or kerosene fuels of good quality, i.e. complying with the 2009 specifications, i.e. having less than 10 ppm of sulphur and an improved cetane number in the case of gas oil fuel.[0003]The hydrotreatment conversion of feeds obtained from renewable sources uses complex reactions, which are promoted by a hydrogenating catalytic system. These reactions in particular comprise:[0004]hydrogenation of unsaturations,[0005]deoxygenation according to two reaction p...

AI Technical Summary

Benefits of technology

[0056]Preferably, the temperature conditions of the stream at inlet to the first catalytic zone of the first hydrotreatment stage a) of the method according to the invention are adjusted by adding the previously heated petroleum feed. The temperature of the stream entering the first catalytic zone of the first hydrotreatment stage a), said stream being constituted by the mixture of the feed obtained from a renewable source and of the petroleum feed is advantageously comprised between 150 and 260° C. and preferably between 180 and 220° C. and very preferably between 180 and 210° C. These temperature conditions of said ingoing stream can initiate the reaction of hydrogenation of the unsaturations of the triglycerides contained in the feed obtained from a renewable source, while controlling the exothermic effect of these reactions. Thus, the temperature change between said ingoing stream and the effluent leaving the first catalytic zone is advantageously limited so that the temperature of the effluent leaving the first catalytic zone is advantageously comprised between 280 and 370° C., preferably between 280 and 330° C. and more preferably above 300° C.

[0130]The hydrotreated liquid effluent resulting from the method according to the invention is essentially constituted by n-paraffins, which can be incorporated in the gas oil pool. To improve the low-temperature properties of this hydrotreated liquid effluent, a hydroisomerization stage is necessary for transforming the n-paraffins to branched paraffins, which have better low-temperature properties.

Problems solved by technology

However, these applications have several drawbacks.

The first drawback is the application of a single stage for co-processing the vegetable oil and the petroleum base.

In fact, this is limiting for optimum operation of the aforementioned hydrotreatment catalysts, which must effect the reactions of deoxygenation and of hydrodesulphurization simultaneously.

The activity and stability of the catalyst as used in these patents are adversely affected by the formation of the by-products carbon monoxide and carbon dioxide resulting from the reactions of decarboxylation / decarbonylation (elimination of oxygen from feed of renewable origin by formation of carbon monoxide and dioxide) promoted on this type of catalyst under the conditions of pressure and temperature described.

This would lead to overconsumption of utilities for maintaining the high temperatures and accelerated ageing of the catalyst.

However, installation of intermediate stripping is expensive, as it requires additional capital expenditure and more complex management of the gases.

Moreover, the main drawback of this application is still the control of corrosion, linked to the presence of carbon monoxide and dioxide.

Images