JPS59105083A - Selective hydrogenation for diene in pyrolized gasoline - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a hydrogenation process and to the hydrogenated pyrolysis gasoline obtained by such G-filtration.

As may be known, pyrolysis gasoline is a by-product in the production of ethene and/or propene by high temperature pyrolysis (e.g. cracking in the presence of steam) of gaseous or liquid hydrocarbons such as naphtha or gas oil. Obtained as an object.

Pyrolysis gasoline is, on the one hand, extremely unstable due to the presence of a relatively high proportion of highly olefinically unsaturated hydrocarbons, and on the other hand, it is an exceptionally valuable and stable motor gasoline component. Contains aromatics and alkenes with high octane numbers that are themselves useful.

In order to obtain products which can be used for various purposes, for example as stable gasolines with high octane numbers or as raw materials for the production of aromatic compounds, highly olefinically unsaturated products consisting mainly of dienes, for example of the cyclopentadiene type, are used. compounds must be removed from pyrolysis gasoline. This removal can be accomplished by partial hydrogenation of dienes to monoolefins. Hydrogenation of monoolefins generally results in a decrease in octane number, so such Hydrogenation should be avoided as much as possible; furthermore, hydrogen consumption is kept at the desired low level.

The dienes present in the pyrolysis gasoline are selectively converted to hydrogen in two subsequent stages with the aid of a catalyst with hydrogenation activity, such as a supported catalyst containing a metal from Group 6 and/or Group 1 of the Periodic Table of the Elements. can be converted into The length of time such catalysts retain sufficient hydrogenation activity is determined by the length of time that such catalysts retain sufficient hydrogenation activity, particularly in the portion of the first stage catalyst bed closest to the reactor inlet.
Usually unsatisfactory due to gum formation, polymer deposition on the catalyst and increased pressure drop.

The present invention comprises carrying out the first stage in the presence of a supported catalyst with a low hydrogenating Group G metal content; by using a catalyst with a higher Group G metal content in the second stage; give a solution to this problem.

The present invention therefore provides a process for the selective hydrogenation of dienes in pyrolyzed gasoline, in which pyrolyzed kaline is contacted with hydrogen in the presence of a supported catalyst at elevated temperature and pressure in two successive stages; The stage catalyst contains /-j% W/or more of a metal from Group Z of the Periodic Table of the Elements, based on the total catalyst, and the second stage catalyst contains /-1 to % W, based on the total catalyst. The selective hydrogenation process comprises W and/or more metals from Group ZA.

Preferably the first and the first! The catalyst of the step contains, respectively, 30% W and/or more of the Group G metal, based on the total catalyst. The most preferred first and second stage catalysts both contain nickel as the Group G metal.

The support for the first and second stage catalysts suitably consists of a refractory oxide such as alumina, silica or silica-alumina; preferably the silica content is 0-2% W
It is alumina.

The metal may be impregnated, ion-exchanged or (co)precipitated by any method known in the art for the preparation of catalysts containing additional components on a carrier. ] method. A suitable method for preparing such a catalyst is
The carrier material is impregnated in one or more stages with an aqueous solution containing the Group metal salt, followed by drying and smoldering.

The first stage catalyst suitably has a surface area of 100-600 m'/9; most preferably 200-j 00
The surface area is m'/shi.

The finished first and second stage catalysts are typically heated with hydrogen or a hydrogen-containing gas at a temperature of 300 to 300'C.
-'Ig time and then at least partially sulfurized. The sulfidation is carried out by any method known in the art before its use, for example with a mixture of catalyzed hydrogen and hydrogen sulfide, or with hydrogen and a content of gas oil or naphtha or C82 or dimethyl disulfide (
DM])S) Divided by the sulfur compound (5pik
ed) It can be carried out by contacting with a hydrocarbon oil such as naphtha at a temperature of 0 to 300°C.

The process according to the invention can be carried out in both stages in the liquid phase or partly in the gas phase and partly in the liquid phase. Preferably, a fixed catalyst bed is applied in both stages of the process. However, it is also possible to apply the catalyst in a fluidized or expanded bed.

A very suitable embodiment is one in which the pyrolysis gasoline to be completely or substantially liquid-occurred is allowed to flow cocurrently with the hydrogen-containing gas through a fixed catalyst bed.

Often these beds are coated at their inlets with a reaction-inert material to promote uniform distribution of the feedstock, ie, to prevent or reduce channeling through the catalyst bed. Since the inerts will occupy a significant portion of the reaction zone, e.g. up to 15 to 20% or more of the reaction zone volume, their use will affect reactor G and the desired hydrogenation of the feedstock. The cost of inerts that do not contribute in any significant way to the capital expenditure of the hydrogenation process both increase the capital expenditure of the hydrogenation process when the first stage catalyst takes over the function of distributing the feedstock over the catalyst bed. In this case, the use of an inert material layer can be avoided in the first step of the method. To perform this function, the first stage catalyst preferably consists of particles in the form of pellets, spheres, rings or other three-dimensional objects whose smallest dimension is larger than 2 mm. in general,! Beds of catalyst particles with dimensions smaller than 39 mm tend to clog more easily and are less effective at distributing feedstock over the initial contact layer of catalyst, while the use of particles with dimensions larger than 39 mm Resulting in a catalyst with significantly lower activity.

A particularly preferred first stage catalyst is 3-. Consists of spherical particles with a diameter of 23 mm. The use of spherical particles with high abrasion strength results in improved feedstock flow distribution across the catalyst bed and also reduced pressure drop compared to the use of catalyst particles of other shapes. Terms used here″
"Spheroidal" refers to both true round shaped particles and generally prolate spheroidal particles that do not pass the perfectly round shape. Procedures for making these particles are known in the art.

7. The first stage catalyst bed is substantially high in an upright reactor.
5m or more) or this catalyst bed' Second! When a layer of catalyst particles is placed,
It is advantageous that the first stage catalyst particles are crush resistant. Preferably the first stage catalyst is /-'l MPaN
Most preferably it has a volume crushing strength of 5-3 MPa.

The second stage catalyst preferably consists of extrudates with a diameter of -5 mm and a volume crushing strength of 0-3 MPa.

The hydrogen used in both stages of the catalytic hydrogenation may be pure or in the form of a hydrogen-containing gas. The gas used should preferably contain more than 10% hydrogen by volume. Very suitable are, for example, hydrogen-containing gases obtained by catalytic reforming or steam reforming of the canlin fraction, and mixtures of hydrogen and light hydrocarbons. The excess hydrogen-containing gas is advantageously recycled to one or both stages, possibly after previously removing undesired constituents therefrom.

It is very suitable to carry out the catalytic hydrogenation under the following conditions which may be the same or different in both stages:! ;0-300
°C Preferably a temperature in the range of JO-/30″C (7)-,
Total pressure in the range 10-100 bar absolute, preferably 20-0 bar absolute; S-0 bar absolute, preferably 10-0 bar absolute
Hydrogen partial pressure in the range 30 bar absolute: 30-10OON
I pure hydrogen/kg gasoline feedstock preferably 100-1
Hydrogen feed rate in the range of 0OONI/kg feedstock; 0.00000000 per catalyst per hour. /-10 kg gasoline feedstock, preferably in the range of 0.3-3 kg gasoline feedstock per liter of catalyst per hour.

Reaction temperatures above /30'C are less preferred in order to avoid increased polymerization of olefin-type compounds in the feedstock. Hydrogenation of dienes to monoolefins is a strongly exothermic reaction. In order to maintain the reactor temperature within a preferred range, the liquid product is preferably recycled and mixed with the pyrolyzed kalin feedstock. The weight ratio of liquid product recycled to the first stage and pyrolysis gasoline feed to the first stage is suitably 0.5-. 20, especially /-70.

Part 2 of the two-step method according to the present invention! The stages may be carried out in a reaction zone separate from the reaction zone in which the first stage is carried out; preferably both the first and second stage catalysts are alternated in a single reaction zone.

The invention is further illustrated by the following examples.

■ A standpipe reactor is charged with 29'lrn'' of the second stage catalyst in the form of 25 lrn extrudates containing 70% W (based on the total catalyst) of nickel calculated as NiO on a support alumina. , on top of this fixed bed, a support alumina' second NiO
Average diameter If fnm, containing nickel 2.5% w (based on the entire catalyst) calculated as , surface area 230
m'/9 and volume crushing strength/, a 3 cm high layer (9, rCm3) of first stage catalyst spheres of more than 7 MPa was placed. The catalyst was first treated with hydrogen at 375'C for 2j hours and then treated with straight run naphtha (DMDS) in the presence of hydrogen.
In naphtha! ;OOppmw sulfur) at 100°C7
Presulfided for an hour.

A pyrolysis gasoline feedstock having a boiling point range of 30-130°C was mixed with the liquid product from the reactor in a weight ratio of /:5. This mixture, containing 25% W diene and 2% W monoolefin, was preheated and placed in the reactor at a temperature of go'c and a H2 partial pressure of VO absolute bar. 6 kg of this feed was fed. Feed materials/1 1st and 2nd
300 Nl hydrogen/hour space velocity of staged catalyst/hour
kg feed mixture and co-currently directed downwardly across the catalyst bed. During this experiment, the reactor system (where the pressure drop was increased) was applied.
After 0 and 60 days of operation, the liquid product in both cases was below zero. / 3%w diene and 2.2! ;%W
of monoolefins, indicating that the selective hydrogenation of dienes may be carried out in stable operation without the need for frequent replacement of the first and 7' or second stage catalysts.

Comparative Example For comparison, steps 11 and 11 were repeated except that the catalyst in the first stage was replaced with alumina spheres that did not contain nickel. During this experiment the pressure drop in the reactor system increased considerably. After the same operating period (70 days and 60 days, respectively) as in Example G above, the liquid products of the reactor were 0/20% diene, 0.2% w1 monoolefin, 22% 1.2% respectively. Contained 2.9% W. These results are unsatisfactory compared to the embodiments shown in this invention.

Agent's name: Kawahara 1) - Ho

Claims (1)

[Claims] (]) A process for the selective hydrogenation of dienes in pyrolysis gasoline, in which the pyrolysis gasoline is reacted with hydrogen in the presence of a supported catalyst at elevated temperature and pressure in two successive stages. The first stage catalyst is /-5 based on the entire catalyst.
%W of metals from Group G of the Periodic Table of the Elements, and the second stage catalyst contains 3-410%W of metals from Group G, based on the total catalyst. The selective hydrogenation method comprising: 2. The method of claim 1, wherein both the seventh and second stage catalysts contain nickel as the Group G metal. 3. A process as claimed in claim 1 or 2, in which both the first and second stage catalysts contain alumina with a silica content of 0-6% W as support. (4) The method according to any one of claims 1 to 3, wherein the first stage catalyst has a volumetric crushing strength of /-11 MPa. (5) The smallest dimension of the first stage catalyst is 2-30m
The method according to any one of claims 1 to t, comprising particles of m. (6) The method according to claim S, wherein the particles are spherical. (7) A process according to any one of claims 1 to 6, in which both the first and second stage catalysts are placed alternately in a single reaction zone. (8) In both stages, the temperature is 30-300°
C range, total pressure in the range 10-100 absolute bar, hydrogen partial pressure in the range 3-g0 bar absolute, hydrogen feed rate in the range 0-7000 N+ per kg feedstock, and space velocity in the range 0-7000 N+. 8. A process according to any one of claims 1 to 7, wherein the range is 0/-10 kg of feedstock per catalyst per hour.