CS200593B1 - Method of activation and stabilization of the platinum-titan catalyst for the dearomatization of the petroleum fractions - Google Patents

Description

The present invention relates to a process for activating and stabilizing a platinum-titanium catalyst for the dearomatization of petroleum fractions, in particular gasoline or kerosene.

Recently, mixtures of saturated hydrocarbons boiling between 30 ° C and 300 ° C have been used for various purposes in the chemical and other industries, while requiring exceptional purity. The mixtures must be free of sine compounds at all, but also of traces of unsaturated hydrocarbons and aromatic hydrocarbons. The distillation fractions of oil, possibly of secondary origin, have up to 1% of sulfur, tenths of unsaturated hydrocarbons and up to several tens% of aromatics. The removal of sulfur and olefins is relatively easy, and for the final treatment to a saturated hydrocarbon mixture, a mixture of aromatics and saturated hydrocarbons results from the original petroleum fraction. Total removal of aromatics is most elegantly accomplished by hydrogenation, and a number of catalysts operating over a wide range of hydrogen temperatures and pressures are described. E.g. thus, the C5 and C8 hydrocarbon fraction to be isomerized on low-temperature bifunctional catalysts, the kerosene fraction for supersonic aircraft, the hexane fraction for the production of pure n-hexane or the gasoline fraction for the production of technical gasoline etc. is dearomatized. on various carriers at pressures usually above-atmospheric and at elevated temperatures. Catalysts, however, are usually unstable and have a poor life span for long-term operation.

A solution has now been found which can be used to dearomatize petroleum fractions, especially gasoline or kerosene, in long cycles at low temperatures. The platinum-titanium-containing dearomatization catalyst is pre-activated with a dry gas containing hydrogen and light hydrocarbons at elevated temperatures and pressures and, after reduction, stabilized with organic sulfur or hydrogen sulfide compounds together with hydrogen and optionally hydrocarbons. The bimetallic catalyst is activated by heating under a pressure of 0.2 to 5.0 MPa with a gas containing 60 to 99.9% by volume of hydrogen and the remainder of the saturated C 1 to C 8 hydrocarbons having a water content of up to 50 ppm by volume, preferably 10 ppm by volume. at 350 to 400 ° C at a rate of 10 to 30 ° C per hour by direct passage or circulation with a downstream gas drier containing, for example, silica gel, molecular sieve or active alumina, as desiccator, and having a desiccant. deposited with cobalt, nickel, molybdenum and tungsten oxides alone or in combination.

The bimetallic catalyst is stabilized after 2 to 8 hours reduction by the above method by heating with carbon monoxide, mercaptans, sulfides or hydrogen sulfide and circulating hydrogen at 350 to 400 ° C for 2 to 16 hours, adding 0.02 to 0 per catalyst. 5 wt. of sulfur calculated on the catalyst. After the sulfur addition, it is further stabilized with a mixture of saturated hydrocarbons or gasoline fractions, which may be mixtures of C5 and / or C8 hydrocarbons obtained by distillation of crude oil, respectively. the same mixture from the distillation of the products of catalytic reforming of petroleum fractions boiling in the range of 50 to 100 ° C, or 80 to 210 ° C, or 110 to 150 ° C, the stabilization being carried out at temperatures gradually increasing from 350 to 400 ° C to 470 to 520 ° C and under a pressure of 1.5 to 1.5 ° C

3.5 MPa with circulating hydrogen gas dryer connected. The catalyst thus prepared is suitable for the dearomatization of petroleum fractions, in particular gasoline or kerosene, while achieving long operating cycles at low temperatures.

It can be seen that the bimetallic catalyst for dearomatizing petroleum fractions is activated and stabilized in a manner similar to the gasoline reforming process, and that its stabilization during the reforming process may be advantageously utilized, possibly in combination with the regenerative process used in the catalytic reforming process. The process according to the invention produces an optimum platinum grain stabilized in addition by additional metal and sulfur. The catalyst is then productive and stable so that it can be worked long periods before the isomerization of the Cg and / or Cg fraction or before the isolation of pure n-hexane. The process of dearomatization on a bimetallic catalyst containing platinum and titanium-group metals using a new treatment process outperforms the process on a conventional reforming catalyst as well as on some other bimetallic combinations, e.g. Pt-Re.apod. Thus, complete dearomatization can be carried out under conditions where the removal of aromatics on the untreated catalyst is imperfect. In particular, the process is suitable at lower pressures and higher volumetric speeds.

The following is an exemplary embodiment to illustrate the results of the process of the invention. Example

70 ml of a catalyst containing 0.6% Pt were charged to the pressure test apparatus,

0.15% Ti and 0.7% chlorine on gamma alumina. The catalyst was heated by direct passage of a gas containing 98% hydrogen and 2% methane at a rate of 20 ° C per hour to 400 ° C over a 4 hour residence time. It was then contacted with gasoline boiling in the range of 95-175 ° C, carbon monoxide and hydrogen for 4 hours at 30 psi. During this time, 0.1% sulfur was charged to the catalyst. Then at a constant gasoline flow and pressure of 3.0. MPa increased the temperature gradually to 520 ° C and after about 10 days the temperatures decreased to 440 ° C, gasoline stopped dosing and temperatures decreased to 110 ° C and dearomatization of Οθ fraction of this composition was started:

and C ₅ '0.1 wt%.

nC ₅ 0.3 wt.

2M C ₅ 15.3 wt.

3MCg 17.5% wt.

n C ₆ 45.3 wt.

Mc C ₅ 16.1 wt.

C ₆ H ₆ 3.2% wt.

The sulfur content was less than 1 ppm and the bromine index was 820 mg Br / 100 g sample.

Gas chromatography and a colorimetric method, the so-called modified formolite test, which was more sensitive than the thromatographic analysis, were used to monitor the dearomatization activity of the catalyst. It was able to detect 0.05% benzene, ie concentrations that can no longer be determined by chromatography.

The operating temperature at the dearomatization was initially 110 ° C, the Cg fraction volume rate was 1.08 hr ^-1 and the hydrogen gas flow rate was 500: 1 by volume to the feedstock. Already under these conditions, complete dearomatization was achieved with a negative formolite test while reducing the bromine index below 1 mg Br / 100 g sample.

In total, a C ₆ fraction volumetric rate of 0.6 to 3.0 hr ^-1 , a hydrogen to feed ratio of 200 to 1200: 1 vol and pressures of 3.0 to 10 MPa were tested, showing that the catalyst was activated and stabilized by said process is stable and does not change its effectiveness during tests ranging from 300 to 500 hours under severe conditions.

Claims (4)

1. A process for the activation and stabilization of a platinum-titanium catalyst for dearomatizing sulfur and moisture-free petroleum fractions, in particular gasoline or kerosene, carried out at elevated temperature and under hydrogen pressure, characterized in that the platinum-titanium-containing catalyst on active alumina is heated under a pressure of 0.2 to 5.0 MPa in a gas stream containing 60 to 50 bar 99.9% by volume of hydrogen and up to 50 ppm by volume of water successively at 350 to 400 ° C at a rate of 10 to 30 ° C per hour by direct passage or circulation, with a residence time of 2 to 8 hours at 350 to 400 ° C, and contact with carbon disulfide, mercaptans, sulfides, or hydrogen sulfide for 2 to 16 hours at the same temperature while being added to the catalyst. 0.02 to 0.5 wt. sulfur and finally a mixture of saturated hydrocarbons or gasoline fractions in the temperature range of 350 to 470 or up to 520 ° C at a pressure of 1.5 to 3.5 MPa. 2. Process according to claim 1, characterized in that in the circulating gas, in addition to hydrogen, saturated hydrocarbons Q to C5 are present and the preferred water content is 10 ppm by volume. 3. The process of claim 1, wherein the activating and stabilizing circulating gas is dried by sillcagel, molecular sieves or active alumina to which optionally cobalt, nickel, molybdenum and tungsten oxides are deposited alone or in combination. 4. A process according to claim 1, wherein the sine compounds can be contacted with the catalyst either alone or in admixture with gasoline fractions.