The present invention relates to a biomimetic-hybrid solvent system for simultaneous capture of H.sub.2S and CO.sub.2 from any gaseous composition. The present invention also relates to a process for upgradation of biogas to bio CNG by removing gaseous contaminants, including microbial removal of H.sub.2S, to obtained purified CO.sub.2. The biomimetic-hybrid solvent system contains three components selected from tertiary amine compounds, a functional colloidal fluid, and an enzyme mimic.

Processes, systems, and associated control methodologies are disclosed that control the flow of biogas during the biogas cleanup process to create a more consistent flow of biogas through the digester, while also optimizing the output and efficiency of the overall renewable natural gas facility. In representative embodiments, a biogas buffer storage system may be used during the cleanup process to control the pressure and flow rate of biogas. The biogas buffer storage system may monitor and control the biogas flow rate to either bring down or increase the digester pressure, thereby maintaining a normalized biogas flow rate.

Compositions of and methods for producing a modified polyimide-containing compound with an alkyl or acyl group, one method including selecting and preparing a polyimide-containing compound to undergo a Friedel-Crafts alkylation or acylation reaction; carrying out the Friedel-Crafts alkylation or acylation reaction on the polyimide-containing compound to bond an alkyl group or acyl group to a reactive site on an aromatic compound of the polyimide-containing compound; cleaving the polyimide-containing compound to produce modified monomers comprising the alkyl group or the acyl group; and using the modified monomers in a reaction to produce the modified polyimide-containing compound, wherein the alkyl group or the acyl group is present in the modified polyimide-containing compound.

Disclosed herein are carbon molecular sieves and methods of making the same through the pyrolysis of a polymer precursor in the presence of a reactive gas stream including a hydrogen source.

This invention integrates a membrane with a steam reformer such that a membrane is placed between a raw biogas feed, and a steam reformer to supply a retentate of purified methane feed to the steam reformer and the permeate as fuel to the steam reformer,

A process is proposed for separating carbon dioxide from a feed stream containing carbon dioxide, in which at least part of the feed stream is subjected to temperature swing adsorption to obtain a first and a second successive stream, wherein, in each case relative to the feed stream, the first subsequent stream is depleted in carbon dioxide and the second subsequent stream is enriched in carbon dioxide, and at least part of the second subsequent stream is subjected to membrane separation to obtain a third and a fourth subsequent stream, the third subsequent stream being depleted in carbon dioxide and the fourth subsequent stream being enriched in carbon dioxide, in each case relative to the second subsequent stream. A corresponding arrangement is also an object of the invention.

A pressurized CO.sub.2 rich gas is cooled down to condense at least part of the stream in a heat exchanger. A bulk of the CO.sub.2 is separated by partial condensation and distillation in order to obtain at least one non-condensable gas from a separation vessel. The non-condensable gas is optionally heated up to a temperature lower than −20° C. (membranes performances is greatly enhanced by low temperature operation). The non-condensable gas is introduced into a membrane permeation unit, producing a residue stream and a permeate stream (the permeate stream is enriched in CO.sub.2). The permeate stream is recycled to the process, optionally after compression. The method is auto-refrigerated, i. e. no external refrigerant is used to provide cooling below 0° C.

The present invention addresses to the use of NaY zeolite with a Si/Al ratio >2.6 as a solid adsorbent in the process of removing H.sub.2S from natural gas through a PSA process. The described adsorbent has the capacity of removing H.sub.2S from natural gas from offshore exploration platforms, enabling in situ regeneration. The experimental development proved the high capacity of capturing H.sub.2S by the NaY zeolite in consecutive cycles of pressurization, adsorption, depressurization and purging. This capture capacity remains at 74.2% of the initial capacity, remaining stable in subsequent cycles. The structure of the material maintained crystallinity above 95% in use, in 15 consecutive cycles, allowing the reuse of the adsorbent for a prolonged period of operation, preventing the solid from being constantly changed, which is quite common in a non-regenerative process.

An apparatus and process for separating a gas mixture is disclosed. The apparatus includes a plurality of membrane separation stages comprising a first membrane stage, a second membrane stage, and a third membrane stage. Each of the first, second, and third membrane stages are designed to separate a gas stream provided to them into a permeate stream and a retentate stream. The retentate stream provided from the third membrane stage is configured to be withdrawn as a product, further processed, or discarded. The apparatus further includes a gas transport device with an inlet in communication with the gas mixture and an outlet in communication with the first membrane stage. The controller is in communication with at least one measuring device, and the controller adapts a behavior of the gas transport device in response to a measurement of the at least one measuring device.

A gas-separation membrane obtainable from curing a composition comprising one or more curable monomers at least 30 wt % of which are monomer(s) comprising oxyethylene groups, oxypropylene groups and at least two polymerizable groups.