Abstract: An integrated system for the derivation of useful energy from impure steam and/or for use in connection therewith, said steam containing both hydrogen sulfide and an alkaline acting component, such as ammonia, while producing liquid-phase and gaseous-phase effluents from condensation of the impure steam and substantially reducing the emission of sulfur-containing compounds to the environment. Treatment of such effluents to selectively react or bind alkaline acting components in the liquid-phase results in an augmented concentration of hydrogen sulfide in the gaseous-phase and its depletion in the liquid-phase. The gaseous-phase comprising noncondensable gas contaminants and uncondensed water vapor is separated from the liquid-phase steam condensate and treated to remove hydrogen sulfide to produce an environmentally acceptable vent gas which the in part is employed in said treatment of the liquid-phase effluent.

Abstract: The invention relates to a finishing process for the removal of low level concentrations of mercaptans, sulfides and disulfides from a gas stream, especially a natural gas stream. The sulfur compounds are washed from the gas stream with a solution containing hydrogen peroxide, sodium carbonate or sodium hydroxide, and ammonia or an amine.

Abstract: The present invention provides an apparatus and process for separating and removing chemical impurities from air which impurities are difficult to absorb. The apparatus for carrying out the process of the present invention comprises a reaction tower (11, 51, 91) into which the air-gas mixture is fed, aperture means (35, 74, 96) in a wall (16, 60, 98) of the tower, at least one filter means (12, 52, 92) carried in the reaction tower, means for distributing (13, 58, 93) an absorbent medium onto the filter, collecting means (14, 54, 94) beneath the filter for collection of the absorbent medium passing through the filter, and fan means (15, 55, 95) provided in the aperture for creating a flow of air through the reaction tower for the separation of substantially all of the impurities therefrom.

Abstract: Methods for removing acidic gases from gaseous mixtures, such as hydrocarbon containing gaseous mixtures, are disclosed. The method includes washing the gaseous mixtures with a methanol wash stream containing more than about 0.5 weight percent ammonia therein, so as to remove at least a portion of the acidic gases from the gaseous mixtures and to produce a laden methanol stream containing said acidic gases therein, regenerating said laden methanol stream by removing a portion of said acidic gases therefrom, so as to regenerate said wash stream, and recycling the regenerated wash stream.

Abstract: There is disclosed a process for removing sulfur compounds from a gas stream. The process involves passing the gas stream containing the sulfur compounds through a mass of porous material that has deposited upon it a metal oxide, the improvement comprises the continuous or intermittent addition of an oxidizing agent and an amine.

Abstract: A gas purification system has: a first treatment apparatus, which purifies an untreated feed gas, containing toxic ingredients such as HCN gas, H.sub.2 S gas and NH.sub.3 gas, into a primary treated gas by causing the feed gas to contact with an alkaline absorbent liquid; an absorbent-liquid-resuscitation apparatus, which refreshes the absorbent liquid, after absorbing the toxic ingredients, by bubblingly introducing a resuscitation gas; and a second treatment apparatus, which further purifies the primary treated gas into a secondary treated gas by strippingly capturing any possible remnant NH.sub.3 gas still present in the former. The resuscitation gas and the toxic-ingredient-absorbed absorbent liquid are forcibly converged by premix nozzles into combined gas/liquid jets as are injected into the absorbent-liquid-resuscitation apparatus.

Abstract: A novel class of di-secondary aminoethers of the general formula: ##STR1## are disclosed wherein R.sub.1 and R.sub.8 are each independently selected from the group consisting of primary alkyl having 1 to 8 carbon atoms and primary hydroxyalkyl having 2 to 8 carbon atoms, secondary alkyl and secondary hydroxyalkyl radicals having 3 to 8 carbon atoms, tertiary alkyl and tertiary hydroxyalkyl radicals having 4 to 8 carbon atoms, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are each independently selected from the group consisting of hydrogen, C.sub.1 -C.sub.3 alkyl and hydroxyalkyl radicals, with the proviso that R.sub.2, R.sub.3, R.sub.6, and R.sub.7 are C.sub.1 -C.sub.4 alkyl or hydroxyalkyl radicals when R.sub.1 and R.sub.8 are primary alkyl or hydroxyalkyl radicals, and at least one of R.sub.2 or R.sub.3 and R.sub.6 or R.sub.7 are C.sub.1 to C.sub.3 alkyl or hydroxyalkyl radicals when R.sub.1 and R.sub.

Abstract: Regenerative process for the purification of a non-reacting industrial gas stream by removal of trace amounts of carbon dioxide therefrom, comprising contacting said gas stream with non-aqueous liquid solution of at least one member selected from the group consisting of: (a) hydroxides and weak acid salts of sodium, potassium, and lithium and (b) specific liquid aliphatic polyhydric alcohol; separating the purified industrial gas from the reaction products of said contacting step including said solution; increasing said reaction products stream to an elevated temperature up to 200.degree. C.; reducing the partial pressure of carbon dioxide in the vapor phase above said reaction product stream; separating carbon dioxide from said reaction product stream; and recycling the treated reaction product stream to said liquid body of said solution for contacting a further quantity of said industrial gas stream.

Abstract: The present invention relates to an alkaline salt promoter system which includes N-secondary butyl glycine and its use in acid gas scrubbing processes.

Abstract: The present invention relates to an alkaline salt promoter system comprising specific mixtures of sterically hindered monosubstituted alpha-amino acids and tertiary amino acids and its use in acid gas scrubbing processes. The preferred promoter system comprises a mixture of N-secondary butyl glycine and N-methyl-N-secondary butyl glycine.

Abstract: The present invention relates to an alkaline salt promoter system comprising specific mixtures of lower aliphatic mono-substituted alpha amino acids and sterically hindered diamino or triamino compounds and their use in acid gas scrubbing processes. The preferred promoter system comprises a mixture of N-secondary butyl glycine and N-cyclohexyl-1,3-propanediamine or N-cyclohexyl-1, 4-butanediamine.

Abstract: The present invention relates to an alkaline promoter system comprising specific mixtures of nonsterically hindered amino compounds and sterically hindered amino acids and their use in acid gas scrubbing processes. The preferred promoter system comprises a mixture of (i) diethanol amine or 1,6-hexanediamine and (ii) N-secondary butyl glycine or pipecolinic acid.

Abstract: A process for removing hydrogen sulfide from a sour gas stream wherein the sour gas stream is contacted with an aqueous alkali metal hydroxide solution containing a stoichiometric excess of the alkali metal hydroxide to provide a sweet gas substantially free of hydrogen sulfide and a partially spent aqueous alkali metal solution. The partially spent aqueous alkali metal solution is contacted with a second sour gas stream in a countercurrent absorber to provide a second sweet gas and a substantially caustic-free aqueous solution of the alkali metal hydrosulfide.

Abstract: A method of preventing sludge deposition in the treatment of geothermal steam condensate with iron catalyzed/hydrogen peroxide by carrying out the treatment in the presence of an inorganic polyphosphate.

Abstract: Acidic gases containing carbon dioxide are removed from a normally gaseous mixture by absorbing CO.sub.2 from the gaseous mixture with an aqueous solution comprising a basic alkali metal salt or hydroxide and an activator or promoter system for the salt or hydroxide which contains (i) at least one diaminoalcohol of the formula:H.sub.2 N--(CH.sub.2).sub.4 --NRR'wherein R and R' each independently represent a C.sub.1 -C.sub.6 alkyl group and either R or R' or both R and R' have a pendant hydroxyl group, and (ii) an amino acid, and desorbing at least partially the absorbed CO.sub.2 from the aqueous solution.

Abstract: Acidic gases containing carbon dioxide are removed from a normally gaseous mixture by absorbing CO.sub.2 from the gaseous mixture with an aqueous solution comprising a basic alkali metal salt or hydroxide and an activator or promoter system for the salt or hydroxide which contains (i) at least one non-sterically hindered diamine defined as having both a primary and a tertiary amino moiety wherein the primary amino moiety is attached to a primary carbon atom, and (ii) an amino acid, and desorbing at least partially the absorbed CO.sub.2 from the aqueous solution.

Abstract: A gas purification system has: a first treatment apparatus, which purifies an untreated feed gas, containing toxic ingredients such as HCN gas, H.sub.2 S gas and NH.sub.3 gas, into a primary treated gas by causing the feed gas to contact with an alkaline absorbent liquid; an absorbent-liquid-resuscitation apparatus, which refreshes the absorbent liquid, after absorbing the toxic ingredients, by bubblingly introducing a resuscitation gas; and a second treatment apparatus, which further purifies the primary treated gas into a secondary treated gas by strippingly capturing any possible remnant NH.sub.3 gas still present in the former. The resuscitation gas and the toxic-ingredient-absorbed absorbent liquid are forcibly converged by premix nozzles into combined gas/liquid jets as are injected into the absorbent-liquid-resuscitation apparatus.

Abstract: A fuel gas is desulfurized while hot by contact with a molten alkali salt. The salt is regenerated for further use by contact with a recirculating gas stream. The H.sub.2 S and COS picked up by the recirculating gas stream is scrubbed at low temperature in an aqueous alkaline salt scrub system such as hot potash. H.sub.2 S regenerated from the low temperature alkaline scrub system is subsequently converted to sulfur. By combining both high temperature and low temperature alkali scrubbing in a single dual temperature dual alkali (DTDA) process, the best advantages of both scrub techniques are retained whereas the serious disadvantages of molten salt scrubbing are eliminated.

Abstract: An improved sulfur-ammonia process for removing hydrogen sulfide from coke oven gases. In the improved process, a concentrator formerly used for standby operation is used at all normal times as an ammonia scrubber to improve the efficiency of gas separation during normal operation and is used as a concentrator for its intended standby functions during the alternative operations. In its normal function, the concentrator/scrubber functions as a scrubber to strip ammonia gas from recirculating liquid streams and to permit introduction of an ammonia-rich gas into a hydrogen sulfide scrubber to increase the separation efficiency of that unit. In the standby operation, the same concentrator/scrubber serves as a concentrator to concentrate hydrogen sulfide in a "strong liquor" stream for separate recovery as a "strong liquor.

Abstract: An aqueous solution containing from 0.81 to 1.3 moles of piperazine per liter is used as a washing agent for removing impurities such as H.sub.2 S, CO.sub.2 and COS from gases. Piperazine can also be used, in amounts of up to 0.8 mole per liter, together with physical or chemical solvents, to accelerate the absorption of H.sub.2 S, CO.sub.2 and COS. The washing process is used for natural gases, coke-oven gases, gases from the gasification of coal and synthesis gases, of any origin.

Abstract: A method of condensing a gaseous mixture of ammonia carbon dioxide gas and water vapor to produce an ammonium carbonate solution with minimum formation of ammonium carbamate includes passing the gaseous mixture into a condenser and cooling the condensing surface to cause the gaseous mixture to condense to form ammonium carbonate solution at a temperature at which formation of solid ammonium carbamate may occur. An aqueous liquid is discharged onto the condensing surface of the condenser, the liquid having an ammonia concentration below about 260 grams per liter to maintain the concentration of ammonia and carbon dioxide on the condensing surface below a concentration at which ammonium carbamate tends to form.

Abstract: Intimate and efficient contacting of plural, physically disparate phases, e.g., a gas and a liquid, is achieved by contacting the phases cocurrently in a column. The gas phase is introduced at a velocity between its phase transition inversion point (T) and multiple critical point (M.sub.c) velocities, which velocity is sufficient to create a dispersion of the second phase, i.e., the liquid phase, in the gas and thereby establish at most the following zones, from bottom to top, in the column: a bottom zone of constant liquid concentration designated the emulsion zone, a zone of decreasing liquid concentration, and a zone of constant liquid concentration wherein the liquid exists in the form of droplets. The feed velocity of the liquid is adjusted accordingly to provide a mass liquid concentration value in the emulsion that is between the mass liquid concentration value transition inversion point and multiple critical point values.

Abstract: H.sub.2 S is removed from a stream of gas such as coal gas at a relatively elevated temperature (300.degree.-400.degree. F.) in a process which employs sulfates or hydroxides of nickel, iron, or zinc as sulfur absorbents. The absorbents are converted to metal sulfides during the absorption process and are regenerated by aeration. Acids produced during sulfur absorption and absorbent regeneration steps are neutralized through the addition of a base. In a preferred embodiment ammonia is also removed and elemental sulfur is produced during the process.

Abstract: A process is disclosed for the purification of an inert or non-reacting gas such as lower mono-olefins by the removal of trace amounts of reacting impurities such as carbon dioxide therefrom, comprising passing said gas through an essentially non-aqueous liquid solution of alkali or alkaline earth metal hydroxides and/or weak acid salts and certain selected liquid polyhydric alcohols.

Abstract: This invention relates to a process for the removal of sulfur compounds from a gas stream. More specifically, this invention relates to an improvement in the iron oxide method of sulfur removal from a gas stream through the use of hydrogen peroxide.

Abstract: A nitrogen base is separated from the sulfur-containing product of a gas phase reaction between a basic nitrogen compound and at least one of a hydrosulfide and sulfur dioxide by washing the product of the reaction, followed by basification and stripping of the wash liquid. In another embodiment, the nitrogen base is displaced from the sulfur-containing product with anhydrous ammonia.

Abstract: A process for releasing ammonia which is bound in coal water using a pre-desulfurization plant having ammonia and hydrogen sulfide scrubbers through which crude coking plant gas is passed comprises circulating the crude coke oven gases through the hydrogen sulfide scrubber and the ammonia scrubber in succession, directing the coal water first through the ammonia scrubber while the crude coking plant gases are being also circulated therethrough after passing it first through the hydrogen sulfide scrubber. An alkali solution is also circulated through the ammonia scrubber to enrich the solution with acid components and to liberate ammonia bound in the coal water directing the coal water which has been enriched from the ammonia scrubber into the hydrogen sulfide scrubber. The process is characterized by the fact that the alkali solution which has first served for the hydrogen sulfide scrubber is added to the ammonia hydrogen sulfide scrubber.

Abstract: A cyclic urea reaction product forms as a by-product of a hindered amine acid gas scrubbing process and results in an ultimate buildup of the material in the circulating amine scrubbing solution. The buildup of this material has a deleterious effect on acid gas removal rates and accordingly, results in inefficient acid gas removal. In the process of the present invention, the cyclic urea degradation product is removed from the circulating solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.

Abstract: Acidic gases such as carbon dioxide are removed from a gaseous mixture including the acidic component by contacting the gaseous mixture in a scrubbing system with an acid absorbing solution comprising a basic alkali metal compound and an activator, during which process at least a portion of the activator is converted to cyclic urea. At least a portion of the scrubbing solution is transferred to a thermal conversion zone wherein at least a portion of the cyclic urea is converted back to the activator afterwhich the scrubbing solution is returned to the scrubbing system from the thermal conversion zone.

Abstract: Acidic gases such as carbon dioxide are removed from a normally gaseous mixture including the acidic component by contacting the gaseous mixture in an absorption zone with an acid absorbing scrubbing solution comprising a basic alkali metal compound and an activator for the compound, during which process at least a portion of the activator is converted to a cyclic urea. The solution is then transferred to the desorption zone to remove at least a portion of the absorbed acidic component. At least a portion of the partially desorbed scrubbing solution containing the cyclic urea is transferred from the desorption zone to a thermal conversion zone maintained at an elevated temperature wherein at least a portion of the cyclic urea is converted back to the activator.

Abstract: A method of cleaning hot gases, especially industrial waste gases, accord to which the gases to be cleaned are passed between plates or discs rotatable about an axis and arranged in spaced relationship to each other, e.g. spaced from each other by a few millimeters. At least one component to be separated from the gases to be cleaned is adapted to form a compound with a layer of a solid substance which has been deposited upon the surface of the plates as a liquid, especially as an aqueous solution, and has been dried. The solution forming the layer of solid substance is sprayed upon the plate surface or at least portions thereof. After reaction of the layer of solid substance with the gases, the layer of solid substance is at least partially withdrawn from the gas space between the respective adjacent plates.

Abstract: An aqueous solution of a zinc salt is used to selectively remove hydrogen sulfide from a gas mixture. An insoluble basic zinc compound is added to the solution to regenerate, or replenish, the salt. A dispersant is added to both decrease the surface tension of the liquid and reduce the degree of hydration of the basic compound, thereby retarding significantly the agglomeration, settling and loss of the basic zinc compound.

Abstract: An improved process for removing carbon dioxide from a gaseous feed including carbon dioxide is described. The carbon dioxide is removed from a gaseous feed by contacting the feed in a contacting zone with a scrubbing solution comprising a sterically hindered amine and an alkali metal salt or alkali metal hydroxide, which at least partially absorbs the carbon dioxide. The scrubbing solution subsequently is desorbed and separated into a two-phase liquid system, an upper phase relatively rich in sterically hindered amine and having a relatively high ratio of alkali bicarbonate to alkali carbonate and a lower liquid phase having a relatively low ratio of alkali bicarbonate to alkali carbonate. The lower liquid phase is returned to the contacting zone at a location above that at which the upper liquid phase is returned to the contacting zone.

Abstract: Wet separation at high temperatures of acidic impurities from gases. The gases are scrubbed with a melt of an alkali metal compound in which a solid alkaline earth metal compound is dispersed.

Abstract: Carbon dioxide containing acidic gases are removed from a normally gaseous mixture by a process comprising contacting the normally gaseous mixture with an aqueous solution comprising (a) a basic alkali metal salt or hydroxide and (b) an activator for said basic salt or alkali metal salt or hydroxide comprising at least one sterically hindered amine.

Abstract: Waste gases are purged by adding to the gas while it flows through an abser a neutralizing agent together with water and then subjecting the gas to cooling so as to evaporate the added liquid. The adsorption then results in a reaction with the neutralizing agent whereby dry salts are formed which are removed from the process. The temperature of the waste gas is automatically and continuously measured and the volume of the water is adjusted automatically and continously in accordance with the temperature measurements. The amount of waste gases is furthermore automatically and continuously measured, preferably at several places of the process, and the amount of neutralizing agent is continuously and automatically adjusted to the latter measurements so as to obtain always the stoichiometric equivalent for the reaction with the pollutants.

Abstract: A waste flue gas cleaning method and an apparatus for practicing said method, in which a reactant solution is sprayed into a waste flue gas introduced into a spray tower, whereby a toxic component in the flue gas is caused to be absorbed in and react with the droplets of the sprayed reactant solution, and the water contained in the droplets is vaporized and the reaction products are dried into solid particles by the sensible heat of said flue gas. A series of the above operation is accomplished within the spray tower while maintaining the outlet gas temperature always above the dew point of the flue gas, and the solid particles of the reaction products are removed from the flue gas by an after dust collector.

Abstract: High temperature reducing gas is scrubbed of H.sub.2 S and other gaseous sulfur compounds at high temperature (>800.degree. K.) in a highly efficient regenerative process. The scrubbing is effected in at least two sequential stages. The first stage scrubbing medium is a molten salt comprised essentially of molten alkali carbonates, sulfides, and hydroxides. The second stage is optionally either a metallic melt comprised of copper or a second molten salt. The copper melt is regenerated with air. The salt melts are regenerated with steam and/or CO.sub.2. When two or more salt stages are used, they are regenerated stagewise countercurrently to the scrubbing sequence.

Abstract: Certain impure steams, especially those from geothermal sources, are polluted with hydrogen sulfide, ammonia, carbon dioxide, other gases, and finely divided particulate solid matter in a form resembling dust or smoke. These contaminants reduce the efficiency of the steam as a heat transfer fluid, are detrimental to equipment utilizing steam as an energy source, and result in environmental pollution or expensive requirements for limiting the same. By the invention herein so polluted steam is selectively processed in the gaseous state upstream of said equipment to remove hydrogen sulfide therefrom, with or without removing other pollutants, to reduce environmental pollution from effluents thereof, to recover valuable materials therefrom, and to improve the utility of the steam as an energy source.

Abstract: An aqueous solution comprising one or more sulfur-containing anions is introduced into a diaphragmless, mercury, electrolytic cell wherein, in the presence of an impressed direct electric current, the sulfur-containing anions are electro-chemically converted to elemental sulfur. The invention will be found most advantageous in treating spent aqueous absorbents recovered from processes for removing SO.sub.2 and SO.sub.3 from stack gases.

Abstract: A cyclic urea reaction product forms as a by-product of a hindered amine acid gas scrubbing process and results in an ultimate buildup of the material in the circulating amine scrubbing solution. The buildup of this material has a deleterious effect on acid gas removal rates and accordingly, results in inefficient acid gas removal. In the process of the present invention, the cyclic urea degradation product is removed from the circulating solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.

Abstract: A process for reducing the hydrogen sulfide content of steam, such as steam produced from a subterranean geothermal reservoir, in which the steam is contacted with an aqueous, alkaline solution having a temperature approximating that of the steam to absorb hydrogen sulfide from the steam which is thereafter discharged or utilized in a power generation plant. Hydrogen peroxide is introduced into a cooled portion of the aqueous, alkaline solution to reduce the hydrogen sulfide content thereof and then the aqueous alkaline solution is heated to about the temperature of the steam and recycled into contact with the hydrogen sulfide-containing steam. The temperature of the cooled portion of the aqueous, alkaline solution into which hydrogen peroxide is introduced is such that thermal decomposition of hydrogen peroxide is substantially prevented.

Abstract: H.sub.2 S and CO.sub.2 from a waste gas are absorbed in an ammoniacal or alkali metal hydroxide solution. The resultant sodium, potassium or ammonium sulfide solution is reacted with pulverized copper oxide and the resultant copper sulfide precipitate is separated and the resultant solution of increased sodium hydroxide, potassium hydroxide or ammonia content is recycled as absorbent for hydrogen sulfide and CO.sub.2. The copper sulfide is roasted to form recyclable copper oxide and product sulfur dioxide.

Abstract: A method for removing sulfur dioxide from flue gases by simultaneous absorption and oxidation in an aqueous absorbent. An enclosed body of an aqueous liquid absorbent for the sulfur dioxide is provided and the flue gas is sparged into an upper portion of the liquid absorbent to form a first zone thereof. An oxygen-containing gas is introduced into a lower portion of the liquid absorbent to form a second zone of the liquid absorbent that is below the first zone of the liquid absorbent and which has an apparent density that is higher than that of the first zone. The oxygen-containing absorbent from the second zone is circulated to the first zone near the point of the flue gas introduction and an alkaline material reactive with the sulfur dioxide in the liquid absorbent is introduced into the body of liquid absorbent thereby fixing the sulfur dioxide in the liquid absorbent in the form of a sulfate. The sulfate is subsequently removed from the body of aqueous liquid absorbent.

Abstract: A process for reducing the hydrogen sulfide content of geothermal steam during a drilling operation by injecting hydrogen peroxide and an alkali metal hydroxide or calcium hydroxide into a flowing stream containing geothermal steam. Environmentally harmless reaction products are thus formed and the emission of hydrogen sulfide during drilling operations is substantially abated.

Abstract: Certain impure streams, especially those from geothermal sources, are polluted with hydrogen sulfide, ammonia, carbon dioxide, other gases, and finely divided particulate solid matter in a form resembling dust or smoke. These contaminants reduce the efficiency of the steam as a heat transfer fluid, are detrimental to equipment utilizing steam as an energy source, and result in environmental pollution or expensive requirements for limiting the same. Herein so polluted steam is selectively processed in the gaseous state upstream of said equipment to remove hydrogen sulfide therefrom, with or without removing other pollutants, to recover valuable materials therefrom, and to improve the utility of the steam as an energy source. This is done by contacting a flow of the steam with aqueous liquid reactant media consisting essentially of one or more reactive compounds of certain metals which form solid metal sulfide reaction products and which preferably are electropositive with respect to hydrogen.

Abstract: Novel process for removing polymer from aqueous absorbent solutions used to contact organic gas-containing gas streams comprising the steps of adjusting the polymer-containing aqueous absorbent solutions to a pH of not more than about 8.5, preferably not more than about 7.5, for example, about 6.0 to about 8.5, preferably about 7.0 to about 7.5, and removing the polymer from the resulting solutions by decantation and/or filtration. The novel process is particularly applicable to the system of removing acid gas from hydrocarbon-containing feed gases which contain one or more polymerizable components wherein the feed gas is contacted with an aqueous absorbent solution which absorbs the acid gas and, thereafter, the absorbent solution is stripped to rid it of said acid gas. The adjustment of pH can be accomplished by increasing the acid gas loading in the aqueous absorbent or by adding an acid, preferably one which will not form a heat stable salt with the absorbent. The pH adjustment, e.g.

Abstract: Carbon dioxide containing acidic gases are removed from a normally gaseous mixture by a process comprising contacting the normally gaseous mixture with an aqueous solution comprising (a) a basic alkali metal salt or hydroxide and (b) an activator for said basic salt or alkali metal salt or hydroxide comprising at least one sterically hindered amine.

Abstract: Acidic components are removed from gaseous mixtures by contacting the gaseous mixture with an aqueous solution comprising (1) a basic salt and (2) an activator for said basic salt comprising at least one sterically hindered amine and an aminoacid which is a cosolvent for the sterically hindered amines. The aminoacid serves to prevent phase separation of the aqueous solution at high temperatures and low fractional conversions during the contacting.

Abstract: A hybrid physical-chemical absorbent process using the interrelation between a physical solvent and a H.sub.2 S selective chemical solvent for removal of CO.sub.2 and sulfur containing compounds, principally H.sub.2 S from a mixed gas stream. This process is especially useful in processes such as coal gasification where the incoming stream to the acid gas removal process is at about 1100 psia, 70.degree. F., contains about 15 to 40 mole percent CO.sub.2 at a mole ratio of CO.sub.2 /H.sub.2 S of about 25 to 50. In such cases the product stream contains less than 1 ppm sulfur and less than 3 mole percent CO.sub.2 which is suitable for production of substitute natural gas while the CO.sub.2 atmospheric effluent contains less than 7 ppm sulfur.