KR860000422B1 - Process for producing mixture of methanol and higher alcohols - Google Patents

Abstract

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Description

Process for preparing methanol and higher alcohol mixture

The present invention relates to a process for producing methanol and higher alcohols and to mixtures obtained by the present invention. The mixture according to the invention is used as a medium of gasoline and can also be used as fuel in an internal combustion engine and mixed in various percentages in gasoline.

Many methods for producing methanol mixed with higher alcohols are known, but they generally have the disadvantage of requiring a high operating pressure of 17, 000-35, 000 KPa. Such high pressure operation has a disadvantage of high facility cost and operation cost. . Literature on high-pressure operation is, for example, the text of Natta, published by Reynolds in 1957, Vol. 5, page 136, in which the capacity is significantly reduced when preparing higher alcohols. Therefore, it is clearly stated that the synthesis should be carried out under high pressure, i.e. the higher the demand for higher alcohol, the more the pressure should be increased. Nata's technology is a paper published by PG Laux at the International Symposium on Alcohol Fuel Technology held in Olfsburg, Nov. 21-23, 1977, entitled "The Catalytic Production and Generation Mechanism of Methyl Fuel." The amount of isobutanol increased from 1.86% at 390 ° C and 176kg / cm2 to 6.14% at 390 ° C and 302kg / cm2.

It is clear from conventional methods that, according to thermodynamic theory, a mixture of methanol and higher alcohol can only be produced when operated under high pressure. The surprising fact found this time is that methanol and higher alcohol mixtures can be produced under low mixing and the higher alcohol content of the mixture is higher than that obtained under high pressure by known methods. The mixtures obtained by this method are superior to the known mixtures, and because of the higher content of higher alcohols, the water is melted and added to gasoline, which is superior to the known mixtures.

Methanol alone cannot be mixed with gasoline, and a mixture of methanol and higher alcohols is produced and added to gasoline because of a certain amount of water that is always present in gasoline, which comes from the water used to clean the refinery's pipes. Or from moisture in the air. When used alone, methanol is mixed with water present in the gasoline and liberated from the gasoline to form two layers in the tank of the car, the gasoline layer and the methanol and water layers. Under these circumstances, if the layers of methanol and water are dispersed instead of gasoline, engine operation becomes difficult.

It is known that the presence of higher alcohols dissolves methanol in the presence of water in gasoline to form a homogeneous mixture. The mixture according to the invention has a content of higher alcohol of 25-65% by weight and dissolves methanol even when the content of water in gasoline is extremely high.

Generally in conventional mixtures comprising 10% by weight higher alcohols, the mixtures according to the invention at an alcohol / hydrocarbon ratio of 20:80 and at -80 ° C. are allowed at least 2,500 ppm to 5,000 ppm or more of water.

It is an object of the present invention to provide a process for preparing methanol and higher alcohols containing 35-75% by weight of methanol on an anhydride basis, which process comprises a catalyst based on chromium, zinc and at least one alkali metal. H ₂ : CO ratio in the reaction zone containing 0.1-20, in particular 0.5-5 hydrogen and carbon monoxide and possibly CO ₂ and inert gas, temperature of 300-500 ℃ especially 350-450 ℃ and 2, 0000-16 , 000KPa and especially injecting under a pressure of 5,000-13, 000KPa.

The catalyst used according to the invention consists of chromium, zinc and at least one alkali metal as described above and the calculated weight ratio of oxide of Zn to Cr is 5: 1-1: 1 and the alkali metal is preferably potassium The amount of alkali metal calculated as oxide is 0.5-5% by weight of the total weight of the elements calculated as oxide.

The preparation of the catalyst can be accomplished in several ways, for example by precipitating a nitrate solution of chromium and zinc with NH ₃ or reacting with chromic acid in an aqueous suspension of zinc oxide, followed by drying or spraying in an oven and heat treatment. The catalyst is extruded to form pellets or granules in different sizes and shapes depending on the characteristics of the reactor used, and the porosity of the catalyst is also controlled.

Alkali metals are introduced by combining the already formed Zn-Cr catalyst with an aqueous solution of hydroxides, carbonates, acetates, formates and other organic salts. Another method may be prepared by reacting a dichromate mixture of ammonium dichromate and an alkali metal with zinc oxide in such a proportion that the final catalyst may contain the desired amount of alkali metal oxide.

Reduction of the catalyst before or after the introduction of the alkali metal requires special care, that is, preferably dilution of a reducing gas such as hydrogen with an inert gas such as nitrogen and controlled so that the temperature on the catalyst does not exceed 350 ° C.

Another object of the present invention is to provide a mixture of methanol and higher alcohol.

The mixture according to the invention has a weight of 35-75% methanol, 2-5% ethanol, 3-12% n-propanol, 10-30% isobutanol and 5-25% at least 5 carbon atoms. Consists of other higher alcohols.

All percentages are calculated on the basis of anhydrides which are produced as byproducts in the reaction and ignore the water present.

With regard to the above-mentioned concentration range, it was observed that the lower value of the higher alcohol concentration and the corresponding higher value of the methanol concentration were made at a higher pressure in the pressure range used according to the present invention. As a result, the highest value of the higher alcohol concentration and the lowest value of the methanol concentration are obtained in the low pressure range.

In order to better understand the present invention, some embodiments will be described, which are not intended to limit the present invention.

Example 1

의 증류수에 736g의 산화아연을 넣은 수용성 스러리를 따로 제조하여, 세차게 교반시키면서 3 산화크롬의 용액을 산화아연 스러리에 첨가하고, 수시간 교반하여 완전히 균일한 혼합물을 만든다. 염기성 크롬산아연을 여과지상에서 수집하여 건조한 분말을 스테아린산아연으로 구성된 결합제와 혼합하여 혼합물을 페레트로 만든다. 6mm 직경을 가진 페레트를 식초산칼륨의 수용액에 침지시킨 다음 환원시켰을 때 K₂O의 함량이 2.5중량%가 되도록 처리한다.242.5 g of chromium trioxide are dissolved in distilled water to give a solution having a concentration of 30% by weight. 2

A water-soluble slurry containing 736 g of zinc oxide in distilled water was separately prepared. A solution of chromium trioxide was added to the zinc oxide slurry with vigorous stirring, followed by stirring for several hours to form a completely uniform mixture. The basic zinc chromate is collected on the filter paper and the dry powder is mixed with a binder composed of zinc stearate to make the mixture ferret. Ferrets with a diameter of 6 mm were immersed in an aqueous solution of potassium vinegar and then treated to reduce the K ₂ O content to 2.5% by weight.

It is dried to remove the impregnated water and then reduced in a reactor suitable for synthesis. A 100 cm 3 ferret is injected into a stainless steel tube reactor submerged in a fluid sand bath and heated to 300 ° C. in a nitrogen stream containing 2% of hydrogen, taking care not to exceed the temperature of 350 ° C. or more upon reduction.

Reduction requires a relatively long time, i.e. 24 hours, and upon reduction the catalyst should not be exposed to air. The chemical analysis of the reduced catalyst is as follows. That is, ZnO = 77.3% -Cr ₂ O ₃ = 19.0% -K ₂ O = 2.4% -400 ° C. heat treatment loss = 1.3%, all percentages are by weight and the surface area is 12 m 2 / g.

The obtained catalyst is used for the preparation of methanol and higher alcohol as in the following example.

Example 2

A synthesis gas having the following composition on a molar basis is injected into a reactor, described in Example 1 and containing 100 cm 3 of the catalyst prepared in Example 1.

H ₂ = 69.0% CH ₄ = 0.1%

CO = 30.5% N ₂ = 0.3%

CO ₂ = 0.1%

The temperature on the catalyst is maintained at 390 ° -420 ° C and tested four times under pressures of 5, 000 KPa, 7, 000 KPa, 9, 000 KPa and 13, 000 KPa, respectively. In each experiment, the liquid reaction product is separated from the gas by cooling and condensation. do. The analysis of the samples collected after the 24-hour test by gas chromatography is shown in the following table.

[table]

GHSV = gas space time velocity

(+) In this specification and examples, the term higher alcohol includes small amounts of other oxygen-containing compounds that act like alcohol when used as fuel in internal combustion engines.

The total amount of C ₂ alcohol present in the liquid with methanol is 57% at 5,000 KPa, 53.7% at 7.000 KPa, 42.8% at 9, 000 KPa and 31.2% at 13,000 KPa.

Claims (6)

In the method for producing a methanol and higher alcohol mixture by reacting H ₂ and CO at a temperature of 300-500 ℃ in the molar ratio of 0.1 to 20 H ₂ : CO in the presence of CO ₂ and inert gas, 2,000-16 A process for preparing an alcohol mixture, characterized in that it is obtained in the presence of a catalyst based on chromium and zinc and at least one alkali metal at a pressure of 000 KPa. The process of claim 1 wherein the mixture has a methanol content of 35-75% based on the dry weight. The process according to claim 1 or 2, wherein the weight ratio of zinc to chromium on an oxide basis is 5 / 1-1 / 1. The process according to claim 1 or 2, wherein the weight ratio of alkali metal to catalyst metal is 0.5-5% based on the oxide. The method of claim 1 wherein the alkali metal is potassium. The process for producing a mixture according to claim 1 or 2, wherein the mixture of methanol and higher alcohol corresponds to the following composition based on anhydride. Methanol 35-75 wt% Ethanol 2-5% by weight 3-12% by weight of n-propanol 10-30% by weight of isobutanol 5-25% by weight higher alcohol above 5 ℃