NZ198082A

NZ198082A - Producing mixtures of methanol and higher alcohols by reacting hydrogen and carbon monoxide

Info

Publication number: NZ198082A
Application number: NZ198082A
Authority: NZ
Inventors: A Paggini; V Lagana; G Manara; V Fattore
Original assignee: Snam Progetti
Priority date: 1980-09-15
Filing date: 1981-08-18
Publication date: 1984-11-09
Also published as: PH17030A; IT1193555B; NO156007C; ES8206410A1; IE812127L; GB2083469A; BR8105777A; DE3136088C2; CU35516A; BE890341A; KR830007800A; GR74675B; AT375062B; TR22083A; IE51556B1; YU202481A; AU546859B2; RO83096B; PL136284B1; DK396981A

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number 1 98082 1 98082 Priority Datefs): .. I1?: ft. /%P. Complats Spccificstion Fited: Class: 'Q'P.l^Pr^ Publication Data: JD9-N0V P.O. r.o: .. .l&ft 984 ii illliil No.: Date: NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION PROCESS FOR PRODUCING MIXTURES OF METRWCL AND HIGHER ALCOHOLS AND MIXTURES OBTAINED THEREBY Xt/We, S NAMP ROGETTI , S . p . A .a company organized under law' of the Italian Republic of Corso Venezia 16 - Milan, Italy, hereby declare the invention for which iij we pray that a patent may be granted to^'i^/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) 1980S2 la PROCESS FOR PRODUCING MIXTURES OF METHANOL AND HIGHER ALCOHOLS AND MIXTURES OBTAINED THEREBY. This invention relates to a process for the production of methanol and higher alcohols and the mixtures obtained with that process. The mixtures according to the present invention, more particularly, are useful as substitutes of gasoline and can also be admixed therewith in various percentages for use as fuels in internal combustion engines. All pressures herein are absolute pressures. Many processes are known for producing methanol in admixture with higher alcohols. They, however, suffer from the shortcoming of requiring comparatively high working pressures, which are generally comprised between 17,000 and 35,000 KPa and this is a considerable defect both from the point of view of the first cost and the running costs, as it is obvious. On the other hand, the requirement of working under high pressures is well known from the literature and, for example, Natta in "Catalysis", Vol.V, Reinhold Publishing Corp.New York, ( 1957), on page 136, clearly states-that, due to the considerable volume reduction which takes place when producing higher alcohols, the synthesis must be effected under high pressures: ob 198032 2. viously the more higher alcohols are requested, the more an increase of pressure should encourage their formation. The statements by Natta are corroborated by Table VII of the paper presented by P.G.Laux at the International Symposium on alcohol fuel technology, Wolfsburg, 21 to 23 November, 1977, having the title: "The catalytic production and mechanism of formation of methyl fuel", where the amount of isobutanol is increas- 171 2 2 ed from a percentage of 1.8652 at 390°C and 176 kg/cm , to a percentage of 6,14^ at 390°C and 302 kg/cm . The conventional art thus clearly shows that the production of mixtures of methanol and higher alcohols is possible only when working under high pressures, according to the teachings of thermodynamics. 15 It has now surprisingly been found that the product ion of mixtures of methanol and higher alcohols can be carried out also under reduced pressures and that such mixtures have a content of higher alcohols which is considerably higher than that which is obtained under the high 20 pressures used by the known art. The mixtures thus obtained fulfil, better than the known mixtures, the task of solu-bilizing water due to their higher content of higher alcohols and act in the same way as the known mixtures v.-hen added to the gasoline, while their production cost is con— 25 siderably lower due to the conditions of reduced pressures under which they are produced. The reason why methanol is never used alone in admixture with gasoline and thus mixtures of methanol and higher alcohols are produced to be l'!^ VrM 17APRi984t/ lOO 0O O I y o u o l added to gasolines, lies in the fact that a certain amount of water is always present in gasoline, said water deriving most usually from the water used for washing the pipings in the refineries, or from the moist-5 ure in the air. Methanol, when used alone, is admixed with the water which is present in the gasoline and is split from gasoline, so that in the tanks of the cars two layers are formed, viz. one of gasoline and the other of methanol and water. Under these circumstances, the en— 10 gines run with great difficulties when the layer of methanol and water is dispensed instead of gasoline. It is known that the presence of higher alcohols permits to solubilize methanol when water is present in gasoline, because thoroughly homogeneous mixtures are thus 15 formed. The mixtures according to the invention have a content of higher alcohols comprised between 2552 and 65$ by wt and permit that methanol may be solubilized even if the water content of gasolines is extremely high. With the mixtures of the prior art, which generally 20 contain 10% of higher alcohols by wt, it is possible to tolerate, at —l8°C, 1000 parts per million(ppm) of water with a ratio alcohols/hydrocarbons of 20:80. With the same ratio of 20:80 and at -l8°C, the mixtures according to the invention permit that from a minimum of 2,500 ppm to may 25 more than 5>000 ppm of water/be tolera-ted. An object of the present invention is to provide a process for the production of mixtures of methanol and higher alcohols, containing from 35% to 75% by wt of methanol on 4. i o o 0 Q ? 1 > u u U L 10 an anhydrous base, comprising the step of feeding to a reaction zone containing a catalyst based on chrcmium, zinc and at least one alkali metal, hydrogen and carbon monoxide, and possibly C02 and inert gases, with a molar ratio H^iCP ~ . comprisedbetween 0.1 and 20, preferably betwoon 0,5 and 5, at a temperature maintained in the range between 300°C and 500°C, preferably between 350°C and 450°C and under a pressure comprised between 2000 and 16000 KPa, preferably between 5000 and 13000 KPa. The catalyst used according to the invention is composed, as outlined above, of chromium and zinc and at least one alkali metal and the ratio of Zn to Cr by wt, considered as oxides, is preferably comprised between 5:1 and 1:1, the alkali metal being preferably potassium and 15 the amount of alkali metals, considered as oxides, is from 0.5/s to 5% by wt relative to the total wt of the elements considered as oxides. The preparation of the catalyst may be effected in a number of ways. 20 By way of example, there can be mentioned the preci pitation with from the solutions of nitrates of chro mium and zinc, or the attack with chromic acid, of aqueous suspensions of zinc oxide. The catalyst can be dried in an oven or by atomization and then subjected to firing. 25 The catalyst can be extruded, pelletizod or granulated in different sizes and shapes consistently with the characteristics of the reactor in which it must be used, its porosity being appropriately regulated. & A 17 APR 1984^ .v 198032 The alkali metals are introduced by impregnating an already formed Zn-Cr catalyst with aqueous solutions of hydroxide, carbonate, acetate, formate and other organic salts. As an alternative, the catalyst can 5 be prepared by reacting zinc oxide with mixtures of bichromates of ammonium and of alkali metals in such a ratio that the final catalyst contains the desired quantity of alkali metal oxides. Special care should be taken in the reduction of the jO catalyst, which is carried out before or after the introduction of the alkali metals, by diluting tiie reducing gas, which is preferably hydrogen, with an inert gas, such as nitrogen, and controlling the temperature of the catalytic bed so that it never exceeds 350°C. Anotlier object of the present invention is to provide mixtures of methanol and. higher alcohols. The mixtures according to the invention have a methanol content which varies from 25% to 75% by wt, a content of ethanol from 2% to 5% by wt, a content of n- pro-panol from 2% to 12^ by wt, a content of isobutanol from 10% to 20% by wt, the balance being" composed of other higher alcohols having more than 5 carbon atoms and being from 5% to 25% by wt. All the percentages are calculated on an anhydrous base, that is neglecting the water which is present because it has been produced in the reaction as a by-product. It should be observed, in connection with the concentration ranges reported above, that the lower values of 15 20 25 17 APR 1984 198082 10 6. the concentration for the higher alcohols, and, correspondingly, the higher values of concentration for methanol are experienced with the higher pr-essure of the pressure range used according to the invention. Consequently, the top values of concentration for the higher alcohols and the lowermost values of the concentrations of methanol are obtained with the lower pressure of the range. A few examples will now be reported in order better to illustrate the invention; it being understood that the invention shall not be construed as being limited thereby or thereto. EXAMPLE 1 242.5 g of chromium trioxide are dissolved in dist, water so as to obtain a solution having a concentration of 30£ by wt. An aqueous slurry of 736 g of zinc oxide in two liters of disc, water is separately prepared and is kept under vigorous stirring. The solution of chromium trioxide is added, with stirring, to the zinc oxide slurry and stirring is continued during many hours so as to achieve a complete homogeneization. The basic zinc chromate is collected 011 a filter and the dry powder is admixed with a binder1 composed of zinc stearate and the mixture is pelletized. The pellets, having a diameter of 6 iran, are soaked by an aqueous solution of potassium acetate in such an amount that on the finished and reduced catalyst the content of K^O by wt is about 2.5/5. After drying to remove the impregnation water, the 20 25 198082 7. catalyst is ready for the reduction to be carried out in the same reactor in which the synthesis will be ef-3 fected. 300 cm of pellets are introduced in a stainless steel tubular roactor immersed in a bath of fluidiz-5 ed sand and heated up to 300°C in a nitrogen stream containing about 2% of hydrogen, care being taken to that the temperature during the reduction never exceeds 350°C. The reduction requires a comparatively long time, about 24 hours. Once it has been reduced, the catalyst shall 10 not be exposed to air any more. The chemical analysis of such a reduced catalyst give-s the following results : ZnO = .,77.3% _ Cr2°3 = -i9*0% - K^O = 2.4$ - firing loss at 4.00°C = 1.3%} all the percentages being by wt. 2 The specific surface area is 125 m /g. j5 The catalyst thus obtained is used for the preparat ion of methanol and higher alcohols as shown in the following example : EXAMPLE 2 In the reactor described in Example 1 and contain— 3 20 ing 100 cm of the catalyst as prepared in said example, a synthesis gas is introduced, which has the following composition, on a molar basis : H2 =69.0% CO 30. 5% 25 C02 = 0.1& CII = 0.1% 4 N = 0.3g- The temperature of the catalytic bed. is maintained u 17 APR 1984^ I 98082 8. between 390°C and 420°C. Four tests are carried out, under a pressure of 5,000 KPa, 7,0C|0 KPa, 9,000 ICPa and 13,000 KPa« respectively, In each test the liquid reaction product is separated from the gas by cooling 5 and condensation. The analyses of the average samples collected after a 24_hour test have been made gaschro— matographically on the anhydrous product and gave the results tabulated in the following Table. TABLE Pressure, KPa 5,000 Temperature, °C 409—415 GHSV, h"1 5,500 Methanol, % by wt 43-0 Ethanol, do. 3*7 • n- propanol, do. 9«1 Isobutanol, do. 23.2 Other higher alcohols (+) 21.0 having more than 5 C atoms do. GIISV *= gas space hour velocity (+) In the specification and the example the term higher alcohols is intended to inclose also small amounts of other oxygen-containing compounds, which, to the end of their use as fuels in xntennal combustion engines, behave like alcohols. 7,000 410-422 11,700 . 46.3 3-9 ■ 9.7 22.4 17.7 9,000 400 -415 14,400 57.2 3.4 8.2 17.4 13.8 13,000 390-410 14,400 68.8 2.9 6.5 12. 1 9.7 CO o CO IV) </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 10. The total content of C + alcohols present in the it liquid with methanol is 57% at 5,000 KPa, 53-7% at 7,000 KPa, 42.8% at 9,000 KPa and 31.25? at 13,000 KPa. 11. WHAT WE CLAIM IS: - 198052

1. A process for preparing a methanol/higher alcohol mixture, which comprises reacting hydrogen and carbon monoxide in a f^rCO molar ratio of from 0.1:1 to 20:1 at a temperature of from 300 to 500 C and at a pressure of from 2000 to 16000 KPa, in the presence of a catalyst comprising chromium, zinc and at least one alkali metal.

2. A process according to claim 1, wherein the 1^:00 molar ratio is from 0.5:1 to 5:1.

3. A process according to claim 1 or 2, wherein the temperature is from 350 to 450°C.

4. A process according to any of claims 1 to 3, wherein the pressure is from 5000 to 13000 KPa. I

5. A process according to any of claims 1 to 4, wherein the reaction takes place in the presence of carbon dioxide and/or inert gas.

6. A process according to any of claims 1 to 5 wherein the chromium, zinc and alkali metal(s) of the catalyst are present, at least in part, as oxides thereof.

7. A process according to any of claims 1 to 6, wherein the Zn:Cr weight ratio of the catalyst, calculated as the oxides thereof, is from 5:1 to 1:1.

8. A process according to any of claims 1 to 7, wherein the alkali metal content of the catalyst, calculated as oxide thereof, is from 0.5 to 5% by weight | based on the total weight of the elements calculated as oxides.

9. A process according to any of claims 1 to 8, wherein the alkali metal is potassium. ■fa?

10. A methanol/higher alcohol mixture prepared by a process |/;• ' according to any of claims 1 to 9 . y

11. A mixture according to claim 10 having a methanol content of from 35 to 75% by weight, based on the weight of the mixture excluding the weight of any water therein.

12. A mixture according-to claim-1-1, comprising from 35 to 75% by weight of methanol, from 2 to 5% by weight of ethanol, from 3 to 12% by weight of n-propanol, from 10 to 30% by weight of isobutanol and from 5 to 25% by weight of alcohol(s) having five or more carbon atoms, the percentages being based on the weight of the mixture excluding the weight of any water therein. 12. i 98082

13. A mixture according to claim 10, substantially as herein described with reference to the Examples. </div>