A method to purify a hydrocarbon gas with hydrogen sulfide as an impurity comprises: (a) charging a chamber with a bed of active-metal carbide of a predetermined mesh-size range; (b) conducting the hydrocarbon gas through the bed of active-metal carbide, forming additional hydrocarbon gas by reaction of the active-metal carbide and the hydrogen sulfide; and (c) filtering from the chamber the hydrocarbon gas without the hydrogen sulfide.

A method is provided for reprocessing a petroleum-based waste oil feedstock into diesel fuel. The method includes forming a treated feedstock by (a) filtering the feedstock, thereby removing solids and metals from the feedstock, and (b) dehydrating the feedstock; vaporizing the treated feedstock to produce an oil vapor; passing the oil vapor through at least one catalyst bed and subsequently through a cooler, thereby converting the oil vapor to a hydrocarbon liquid product with a diesel product boiling point range; and removing contaminants from the hydrocarbon liquid product, wherein the contaminants are selected from the group consisting of particulates and color precursors.

Solvent consumption in supercritical ethanol, propanol or butanol treatment of either refined pre-extracted lignin or comparatively impure lignin-rich solid residual from hydrothermally pretreated lignocellulosic biomass can be minimized by conducting the reaction at very high loading of lignin to solvent. Comparatively impure, crude lignin-rich solid residual can be directly converted by supercritical alcohol treatment to significantly diesel-soluble lignin oil without requirement for pre-extraction or pre-solubilisation of lignin or for added reaction promoters such as catalysts, hydrogen donor co-solvents, acids, based or H2 gas. O:C ratio of product oil can readily be obtained using crude lignin residual in such a process at levels 0.20 or lower.

A process is disclosed for the removal of hydrogen sulfide (H.sub.2S) from natural. This process provides for passing a natural gas feedstream comprising H.sub.2S though a regenerable adsorbent media which adsorbs H.sub.2S to provide an H.sub.2S-lean natural gas product and H.sub.2S. The regenerable adsorbent media of the present invention is a tertiary amine functionalized cross-linked macroporous polymeric adsorbent media.

The present invention concerns the use, for gas separation, of at least one zeolite adsorbent material comprising at least one FAU zeolite, said adsorbent having an external surface area greater than 20 m.sup.2.Math.g.sup.−1, a non-zeolite phase (PNZ) content such that 0<PNZ≦30%, and an Si/Al atomic ratio of between 1 and 2.5. The invention also concerns a zeolite adsorbent material having an Si/Al ratio such that 1≦Si/Al<2.5, a mesoporous volume of between 0.08 cm.sup.3.Math.g.sup.−1 and 0.25 cm.sup.3.Math.g.sup.−1, a (Vmicro−Vmeso)/Vmicro ratio of between −0.5 and 1.0, non-inclusive, and a non-zeolite phase (PNZ) content such that 0<PNZ≦30%.

Disclosed is an absorbent containing an amine for absorption of an acid gas in a biogas, and a biogas purification system using the same.

In some embodiments, the present disclosure pertains to methods of capturing CO.sub.2 from an environment by hydrating a porous material with water molecules to the extent thereby to define a preselected region of a plurality of hydrated pores and yet to the extent to allow the preselected region of a plurality of pores of the porous material to uptake gas molecules; positioning the porous material within a CO.sub.2 associated environment; and capturing CO.sub.2 by the hydrated porous material. In some embodiments, the pore volume of the hydrated porous material includes between 90% and 20% of the pre-hydrated pore volume to provide unhydrated pore volume within the porous material for enhanced selective uptake of CO.sub.2 in the CO.sub.2 associated environment. In some embodiments, the step of capturing includes forming CO.sub.2-hydrates within the pores of the porous material, where the CO.sub.2.Math.n/H.sub.2O ratio is n<4.

Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

Disclosed in certain embodiments are methods of removing water from a gas feed stream comprising mercaptans and water during an adsorption step of an adsorption cycle.

Proposed is a pretreatment desulfurization system including a desulfurization agent storage tank for storing a liquid-phase pretreatment desulfurization agent and a metering pump for supplying the liquid-phase pretreatment desulfurization agent from the desulfurization agent storage tank to a fuel supply line through which marine fuel oil is supplied to a marine engine in a predetermined ratio. Since a fluid mixture composed of the marine fuel oil and the pretreatment desulfurization agent is supplied to the marine engine, sulfur oxides are adsorbed and removed during combustion of the fluid mixture.