Patent EP-0203651-A2 (EP)
Inventor: GAZZI LUIGI
IPC: C10L3/10
Filed: 1986-05-14
Abstract: A cryogenic process is disclosed for the selective removal of acidic gases from natural gases or from synthesis gases by adsorption in two towers and cooling of the gas outcoming from the first tower to the purpose of condensing a portion of CO<sub>2</sub> contained in the same gas, which is characterized in that in it a mixture is used constituted by one or more selective solvents selected among low molecular weight esters, alcohols and ethers of the following classes:-esters of alcohols of general formula R,COOR2, wherein R, and R2 are alkyl groups of from 1 to 4 carbon atoms, equal to or different from each other, wherein one or more hydrogen atoms can be substituted by alcoholic groups;-esters of glycols of general formulaorwherein R, and R<sub>2</sub> are alkyl groups having from 1 to 3 carbon atoms, equal to or different from each other, R<sub>3</sub>, R<sub>4</sub>, R<sub>s</sub>, R<sub>6</sub>, equal to or different from each other, are either alkyl groups containing from 1 to 3 carbon atoms or hydrogen atoms, m and n are integers which can have the value 0 or 1;-cyclic esters (lactones) of formulaorwherein R<sub>2</sub>, R<sub>3</sub>, R<sub>4</sub>, R<sub>s</sub>, equal to or different from each other, are alkylene groups wherein one or more hydrogen atoms can also be substituted by alkylic, alcoholic or ether groups;-alcohols of general formulawherein R,, R<sub>2</sub>, R<sub>3</sub>, R<sub>4</sub>, R<sub>s</sub>, R<sub>6</sub>, equal to or different from each other, are alkyl groups having from 1 to 3 carbon atoms or hydroxy groups or hydrogen atoms, and m n are integers which can assume the values 0 and 1;-cyclic ethers such aswherein R2, R<sub>s</sub>, R<sub>6</sub>, equal to or different from each other, are alkyl groups wherein hydrogen can also be substituted by alkyl or methoxy groups, R<sub>3</sub> is either an oxygen atom or an alkylene group wherein hydrogen can also be substituted by alkyl or methoxy groups, R<sub>4</sub> is either equal to R3 or can be absent in case of a pentaatomic ring;-ethers of general formulawherein R, is an alkyl group of from 1 to 4 carbon atoms, R<sub>2</sub> is either an alkyl group of from 1 to 4 carbon atoms or a hydrogen atom , R<sub>3</sub> is either an alkylene group or (CH<sub>2</sub>-O-CH<sub>2</sub>), n is an integer which can have the value 0 or 1;-ethers of general formulawherein R, and R<sub>2</sub>, either equal to or different from each other, are alkyl groups of from 1 to 4 carbon atoms, wherein one or more hydrogen atoms can be substituted by alcoholic groups;-ester-ethers, compounds containing both the functions, of formula:wherein R<sub>3</sub> and R., equal to or different from each other, are alkyl groups having from 1 to 4 carbon atoms, R2 is an alkylene group having from 1 to 4 carbon atoms, R, is either equal to R<sub>2</sub> or equal to R<sub>3</sub>, m and n are integers which can have the value 0 or 1, and by one or more organic compounds selected from:-heptane,-fractions of natural gasolines containing hydrocarbons having a number of carbon atoms comprised within the range of from 5 to 8;-monoaromatic compounds having a number of paraffinic carbon atoms comprised within the range of from 2 to 4, bound to the benzene ring either separately or as one or more linear or branched side chains;-dimethylethers of polyglycols having the glycolic unit -CH<sub>2</sub>-CH-O-repeated from once to five times;-methoxy-and/or ethoxyalcohols, wherein the alcoholic group is a radical having from 1 to 4 carbon atoms in either linear or branched chain.