The invention provides processes for cleaning carbon dioxide-containing process gases from the preparation of vinyl acetate after reaction of ethylene with acetic acid and oxygen in heterogeneously catalyzed, continuous gas phase processes, characterized in that carbon dioxide-containing process gases, for removal of carbon dioxide, are contacted with one or more scrubbing solutions, and one or more scrubbing solutions comprise one or more oxides of metals (metal oxides) selected from the group comprising vanadium, niobium, tantalum, chromium, molybdenum, manganese and arsenic.

A method for reducing pollution in a cement kiln environment and a system for treating cement kiln exhaust gas are provided. The method includes the steps of: treating a cement kiln exhaust gas stream with a treating fluid, such as a water soluble alkaline-earth metal sulfide. In one application, the treating fluid is injected by spraying droplets into the cement kiln exhaust gas stream. A system for treating cement kiln exhaust gas includes a reagent containing a water soluble alkaline-earth metal sulfide in water, and a nozzle to spray the reagent into the cement kiln exhaust gas stream.

The invention relates to a device and method for depleting acidic gases, in particular CO.sub.2, from gas mixtures, in particular respiratory gas, using hydroxide compounds and moisture absorbing substances in the form of super-absorbing polymer or vermiculite.

The invention provides processes for cleaning carbon dioxide-containing process gases from the preparation of vinyl acetate after reaction of ethylene with acetic acid and oxygen in heterogeneously catalyzed, continuous gas phase processes, characterized in that carbon dioxide-containing process gases, for removal of carbon dioxide, are contacted with one or more scrubbing solutions, and one or more scrubbing solutions comprise one or more oxides of metals (metal oxides) selected from the group comprising vanadium, niobium, tantalum, chromium, molybdenum, manganese and arsenic.

In one aspect, the invention provides a method for the capture of at least one acid gas in a composition, the release of said gas from said composition, and the subsequent regeneration of said composition for re-use, said method comprising performing, in order, the steps of: (a) capturing the at least one acid gas by contacting said at least one gas with a capture composition comprising at least one salt of a carboxylic acid and at least one water-miscible non-aqueous solvent; (b) releasing said at least one acid gas by adding at least one protic solvent or agent to said composition; and (c) regenerating the capture composition by partial or complete removal of said added protic solvent or agent from said composition. Optionally, said capture composition comprising at least one salt of a carboxylic acid and at least one water-miscible non-aqueous solvent additionally comprises water or another protic solvent. In another aspect, the invention envisages a composition which additionally comprises at least one protic solvent or agent and release of the at least one acid gas is achieved solely by subjecting the composition to the application of heat or stripping with a stream of air. The method is typically applied to the capture and subsequent release of carbon dioxide, and offers a convenient and simple process which uses inexpensive consumables and offers significant advantages over the methods of the prior art.

A carbon dioxide immobilization system includes: a carbon dioxide capture apparatus in which a solid adsorbent is caused to adsorb carbon dioxide in a first gas, then the solid adsorbent is heated and depressurized, and a second gas containing a higher concentration of carbon dioxide than the first gas does is extracted; a carbonate generation apparatus configured to cause carbon dioxide in the second gas extracted from the carbon dioxide capture apparatus to be reacted with an alkaline earth compound to generate carbonate; and a sensor configured to detect a concentration of carbon dioxide in the second gas is provided. A degree of depressurization in the carbon dioxide capture apparatus is controlled by feedback in such a way that the concentration of carbon dioxide detected by the sensor is maintained within a predetermined target concentration range.

Geomass mediated carbon dioxide (CO.sub.2) sequestering methods and systems are provided. Aspects of the methods include contacting a gaseous source of CO.sub.2 and an aqueous capture ammonia to produce a CO.sub.2 sequestering product and an aqueous ammonium salt, and then contacting the aqueous ammonium salt liquid with a geomass, e.g., alkaline waste product, to regenerate the capture ammonia. Also provided are systems configured for carrying out the methods.

A method for capturing carbon is provided. The method may comprise a process cycle of: a carbonization process, comprising enriching a feed comprising an aqueous medium with carbon from a carbon dioxide source to form a carbon-rich aqueous medium comprising carbonate ions, and a decarbonization process, comprising removing carbon from the carbon-rich aqueous medium by treating the carbon-rich aqueous medium with a cation capable of forming an insoluble carbonate with the carbonate ions, and removing the insoluble carbonate to form a carbon-deficient aqueous medium; wherein the method comprises carrying out the process cycle for multiple times, with the carbon-deficient aqueous medium of a preceding stage making up the feed for the enriching in a subsequent stage, wherein each of the multiple times uses one or more of (a) a different carbon dioxide source, (b) a different pH, and (c) a different cation.