The present invention relates to an adsorbent comprising an alumina support and at least one alkali element, said adsorbent being obtained by introducing at least one alkali element, identical to or different from sodium, onto an alumina support the sodium content of which, expressed as Na.sub.2O equivalent, before the introduction of the alkali element or elements, is comprised between 1000 and 5000 ppm by weight with respect to the total weight of the support. The invention also relates to processes for the preparation of said adsorbent and use thereof in a process for the elimination of acidic molecules such as COS and/or CO.sub.2.

The present invention describes the process of preparing ceramics for the absorption of ACIDIC gases, which worsen the greenhouse effect, that are released in combustion systems, or that are present in closed environments. In relation to carbon dioxide, principal target of the present invention, the process of absorption, transport, processing and transformation of the gas into other products is described. The process uses ceramic materials prepared through the solid mixture of one or more metallic oxides, with one or more binding agents and an expanding agent. The product generated can be processed and the absorbent system regenerated. The carbon dioxide obtained in the processing can be used as analytic or commercial carbonic gas, various carbamates and ammonium carbonate.

The present invention relates to a process for purification of a carbon dioxide feedstock, for example from a production well, which comprises carbon dioxide and gaseous and liquid C.sub.1+ hydrocarbons. Specifically, a carbon dioxide feedstream is passed through one or more separation unit wherein each separation unit removes one or more C.sub.1+ hydrocarbon from the carbon dioxide feedstream to provide a richer carbon dioxide gas stream. The process comprises one or more separation unit which employs an adsorption media and has an adsorption step and a media regeneration step wherein the regeneration step may be operated as a batch process, a semi-continuous process, or a continuous process. One embodiment of this method provides for the use of a different regenerable adsorbent media in two or more separation units.

Provided is a dehumidification apparatus with good energy efficiency. A moisture absorbing material (polymeric moisture absorbing material 24), which absorbs moisture and swells at a temperature not higher than a predetermined temperature sensitive point, while shrinking and releasing condensed water at a temperature higher than the temperature sensitive point as a result of phase transition, is formed so as to be divided into a plurality of segments which are made apart from each other during dehydration. A rotation motor (21) is used to move the moisture absorbing material (polymeric moisture absorbing material 24) between a moisture absorption region (14a) and a dehydration region (14b). In the dehydration region (14b), the moisture absorbing material (polymeric moisture absorbing material 24) is heated by the heater (25).

Provided is a moisture absorbing material, a dehumidifying device, and a dehumidifying method each of which makes it possible to efficiently release absorbed moisture without use of a large quantity of heat. A moisture absorbing material (22) (i) having (a) a first state in which the moisture absorbing material (22) is capable of absorbing moisture and (b) a second state in which the moisture absorbing material (22) releases the moisture absorbed in the first state and (ii) having a property of changing from the first state to the second state in response to an external stimulus and returning from the second state to the first state when the external stimulus disappears, the moisture absorbing material (22) including: first through fourth moisture absorbing bodies (22a) through (22d) which have respective different stimulus response levels and are provided in order of stimulus response level so as to be in contact with one another.

A carbonic acid gas absorbing material on an embodiment includes a liquid carbonic acid gas absorbent and a solid carbonic acid gas absorbent. The liquid carbonic acid gas absorbent is a solution containing a first amine and a solvent. The solid carbonic acid gas absorbent is a second amine of any one among a polyamine, a base material and an amine fixed to the base material, or a polyamine, a base material, and an amine fixed to the base material.

Industrial waste derived adsorbents were obtained by pyrolysis of sewage sludge, metal sludge, waste oil sludge and tobacco waste in some combination. The materials were used as media to remove hydrogen sulfide at room temperature in the presence of moisture. The initial and exhausted adsorbents after the breakthrough tests were characterized using sorption of nitrogen, thermal analysis, XRD, ICP, and surface pH measurements. Mixing tobacco and sludges result in a strong synergy enhancing the catalytic properties of adsorbents. During pyrolysis new mineral phases are formed as a result of solid state reaction between the components of the sludges. High temperature of pyrolysis is beneficial for the adsorbents due to the enhanced activation of carbonaceous phase and chemical stabilization of inorganic phase. Samples obtained at low temperature are sensitive to water, which deactivates their catalytic centers.

A mixed salt composition adapted for use as a sorbent for carbon dioxide removal from a gaseous stream is provided, the composition being in solid form and including magnesium oxide, an alkali metal carbonate, and an alkali metal nitrate, wherein the composition has a molar excess of magnesium characterized by a Mg:X atomic ratio of at least about 3:1, wherein X is the alkali metal. A process for preparing the mixed salt is also provided, the process including mixing a magnesium salt with a solution comprising alkali metal ions, carbonate ions, and nitrate ions to form a slurry or colloid including a solid mixed salt including magnesium carbonate; separating the solid mixed salt from the slurry or colloid to form a wet cake; drying the wet cake to form a dry cake including the solid mixed salt; and calcining the dry cake to form a mixed salt sorbent.

Provided is a method for reusing an adsorbent which can stably exhibit purification ability by regenerating a used absorbent, in order to keep the composition of a purified syngas constant.

The present invention concerns a method for regenerating a zeolite adsorbent which adsorbs a carbon dioxide gas from a syngas comprising the carbon dioxide gas and reduces the concentration of the carbon dioxide gas in the syngas, comprising: a step of recovering a used zeolite adsorbent; a step of calcining the used zeolite adsorbent at a temperature of 300° C. to 600° C. in an oxygen atmosphere to produce a regenerated zeolite adsorbent; and a step of reusing the regenerated zeolite adsorbent.

The invention relates to a process for regeneration of an adsorber (A) by contact with a stream (S1), wherein the stream (S1) is heated in advance by at least two heat exchange units (HEU1) and (HEU2). As outflow of the adsorber (A) a stream (S2) is obtained, which is passed through at least two heat exchange units (HEU1) and (HEU2) traversed by stream (S1), wherein the temperature of stream (S2) fed into each heat exchange unit is higher than the temperature of stream (S1) fed into the heat exchange units (HEU1) and (HEU2), in order to directly transfer heat from stream (S2) to stream (S1).