CA1129440A

CA1129440A - Preparation of olefins from crude methanol

Info

Publication number: CA1129440A
Application number: CA346,043A
Authority: CA
Inventors: Laszlo Marosi; Joachim Stabenow; Matthias Schwarzmann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1979-03-14
Filing date: 1980-02-20
Publication date: 1982-08-10
Also published as: DE2909928A1; EP0016405A1; DE3060088D1; ATE423T1; ES489506A0; EP0016405B1; ES8200320A1; BR8001492A

Abstract

O.Z. 0050/033724 Abstract of the disclosure: A process for the preparation of C2-C5-olefins from crude methanol and/or dimethyl ether by catalytic conversion at an elevated temperature in the presence of a zeolite, containing iron oxide, as the catalyst. The raw material used for the process is undiluted crude methanol and/or dimethyl ether.

Description

ggo Preparation of olefins from crude methanol Recently, endeavors to use methanol for the preparation of olefins have aroused increasing interest. Methanol can easily be prepared from coal by means of well-established technologies, via coal gasification and the preparation of synthesis gas.
Should it prove possible to convért methanol economically to lower olefins, the further conversion processes which are at present conventionally used in the chemical industry could be retained if coal was used as the raw material. Hence, processes have been developed in recent years for preparing olefins from methanol and/or dimethyl ether. Such a process is described, for exampler in German Laid-Open Application DOS 2,615,150 published on October 21, 1976. The catalyst used in this process is the aluminosilicate zeolite ZSM-5, which in fact is a catalyst for aromatization reactions. However, the reaction can be directed toward the formation of olefins by taking various measures, in particular by reducing the residence time. Other measures which favor olefin formation are the dilution of methanol or of dimethyl ether with inert gases, or the dilution of the catalyst with~ inders. Experience shows that high olefin yields can only be achieved if the methanol and/or dimethyl ether is very~greatly diluted with inert gases. Hence, the process is uneconomical. Other processes which have been dis-closed have the disadvantage that the catalyst throughput is low, and that the catalyst carbonizes rapidly. There is therefore .. , ... .. . ~

- 2 - O~Z. 0050/033724 great interest in a simple process which permits complete conversion of crude methanol and/or dimethyl ether into hydrocarbons consisting in the main of C2-C5-olefins.
We have found that C2-C5-olefins are obtained in a simple manner from crude methanol and/or dimethyl ether by catalytic conversion at an elevated temperature in the presence of a zeolite-containing catalyst, if the zeolite contains iron oxide.
In a preferred embodiment, crude methanol is lo reacted over the zeolite catalyst, containing iron oxide, at between atmospheric pressure and about 30 bar, and at from 300 to 700C, preferably from 400 to 650C. Crude methanol for the purposes of the invention means methanol containing up to about 30% by weight of water, ie. the product formad in the synthesis of methanol. Other lower alcohols may also be present in the crude methanol.
The catalyst throughput, expressed in g of methanol and/or dimethyl ether/g of catalyst.h is advantageously selected to be such that the latter compounds are converted as completely as possible, thereby eliminating separation and recycling problems. In general, therefore, the throughput is of the order of from 2 to 50, preferably from 5 to 15, g/g of zeolite.h. However, it is poss-ible to select higher throughputs, or to dilute the starting materials with an inert gas, for example nitro-gen, without adverse effect on the composition of the hydrocarbon mixture formed. At the same time it is a particular advantage of the invention that the conver-sion of crude methanol or dimethyl ether to C2-C5-olefins

- 3 _ o.z. 0050/033724 can be carried out without a diluent.
The zeolites described in German Patent Applica-tion P 28 31 611.2 can be used as zeolite catalysts con-taining iron oxide. These catalysts are distinguished by particularly high activity and selectivity, and in addition by a very long life between successive regenera-tion steps;
The Examples which follow illustrate the process according to the invention.
EXAMPLE
eparation of the zeolite containin~ iron oxide:
lo Three solutions are prepared. Solution 1 con-sists of 326.6 g of technical-grade waterglass (containing 8% by weight of Na20 and 28% by weight of SiO2) and 352 g of water. Solution 2 consists of 300 g of a 50 per cent strength aqueous hexamethylenediamine solution and solution 3 consists of 508.3 g of water, 24.7 g of 96 per cent strength sulfuric acid and 12.4 g of Fe2(S04)3 . 18 H20. Solutions 2 and 3 are successively added to solution 1, whilst stirring. The resulting mixture is heated for 5 days at 150C under its autogenous pressure in a steel autoclave. The resulting product is filtered off, washed and dried at 100C.
Preparation of the catalyst from the zeolite:
The resulting zeolite, containing iron oxide, is mixed with boehmite in a ratio such that the zeolite con-tent in the mixture is about 65% by weight, based on ar,hydrous and amine-free product~

pi~bllsllY~ t~ ~b~ ~ ~9~o 1~ 4~) _ 4 _ o.z. 0050/033724 The mixture is then kneaded with water and extruded to form strands of 1 mm diameter. These are calcined at 540C, then treated with an aqueous ammonium sulfate solution at 80C, filtered off, washed and dried.
Conversion of crude methanol to olefins:
20 g (dry weight) of this catalyst are introduced into a flow-tube reactor of 20 mm diameter and the acti-vity in respect of the conversion o~ crude methanol to olefins is tested. The reaction conditions and experi-mental results are shown in the Table which follows.
The reaction products wereanalyzed by gas chromatography.
Entry temperature 380C
Temperature rise 220C
Pressure ^ 1.4 bar Throughput 200 g of crude methanol/h Total throughput 3,000 g Conversion 95-100%
The reaction product obtained has the following composition:
Liquid hydrocarbons, 15~ by weight, based on CH2 employed Gaseous hydrocarbons, 85% by weight, based on CH2 employed, and containing the following:
Olefins C2 10% by volume C3 50% " "
C4 20% " "
c5 6% 1~ n _ 5 _ o.z. ooso/033724 Paraffins Cl 4% by volume C2 ~ 1%
C3 2%
C4 4% "
Remainder 3% " "

Claims

We claim:- O.Z. 0050/033724

1. A process for the preparation of C2-C5-olefins from crude methanol and/or dimethyl ether by catalytic conversion at an elevated temperature in the presence of a zeolite-containing catalyst, wherein the zeolite contains iron oxide.

2. A process as claimed in claim 1, wherein undilu-ted crude methanol and/or dimethyl ether is used as the starting material.