Desulfurization of natural gas

Desulfurization of natural gas can be achieved by bubbling it through an alkaline solution. Defoamers are added to avoid foaming. 

Desulfurization of fossil fuels was the subject of an authoritative review by J. B. Hyne (Alberta Sulphur Research Institute). This is a topic of increasing importance as Canada relies more and more on sulfur-containing fuels such as tar sands and heavy oils. Hyne reviewed the present state of the chemistry and technology for both precombustion desulfurization of natural gas and crude oils and postcombustion tailgas clean up of coals and cokes. He clearly identified areas of possible future research such as the high temperature-high pressure chemistry pertaining to in-situ desulfurization processes. 

Monoethanolamine is the oldest and probably still the most widely used solvent (Fig. 1). For desulfurization of natural gas, a 10 to 30% aqueous solution of monoethanolamine is normally used and a variety of solvents are available that vary in solvent selectivity for absorption of hydrogen sulfide and carbon dioxide, and this property, as well as the composition of the impurities in the gas being treated, frequently determines the choice of solvent. Some of... 

The present chapter will review the present state of the art and challenges in the ultradeep desulfurization of natural gas, gasoline, jet fuel, diesel, reformate, and syngas from coal gasifier by HDS, selective adsorption, solvent absorption, and ODS, respectively. 

There are many methods for the desulfurization of nature gas, which can be classified into dry desulfurization, wet desulfurization, and catalytic adsorption. In the dry desulfurization, some solid sorbents, such as iron oxide, zinc oxide, activated carbon (AC), zeolites, and molecular sieves, are used. In wet desulfurization method, liquid-phase chemical/physical solvent absorption systems are usually used for scrubbing H2S amine-based processes are subject to equipment corrosion, foaming, amine-solution degradation, and evaporation, and require extensive wastewater treatment. As a result, this sulfur removal technology is complex and capital intensive,44 although the processes are still employed widely in the industry. The desulfurization of coal gasification gas will be reviewed in detail in Section 5.5. In the catalytic-adsorption method, the sulfur compounds are transformed into H2S by catalytic HDS or into elemental sulfur or SOx by selective catalytic oxidation (SCO), and then, the reformed H2S and SOx are removed by the subsequent adsorption. 

Roh et al.116 investigated the desulfurization of natural gas over AC, Fe/AC, BEA zeolite (BEA), and Fe/BEA for fuel cells. Sulfur capacities were obtained from... 

These studies for desulfurization of natural gas at ambient temperature indicate that metal iron-exchanged zeolites might be promising adsorbents, and more work is necessary for the regeneration of the spent metal ion-exchanged zeolites. 

Lampert, J.J. Selective catalytic oxidation A new catalytic approach to the desulfurization of natural gas and liquid petroleum gas for fuel cell reformer applications. Journal of Power Sources, 2004, 131, 27. 

The combustion of sulfur, which is obtained either from natural deposits or from desulfurization of natural gas or crude oil, is carried out in one-stage or two-stage sulfur combustion units at 900-1,050 °C. The combustion unit consists of a combustion chamber followed by a process gas cooler. The SO2 content of the combustion gases is generally up to 11 vol.% aud the O2 conteut is low (but higher than 10%). 

Bhandari DA, Bessho N, Koros WJ. Hollow fiber sorbents for desulfurization of natural gas. Ind Eng Chem Res 2010 49(23) 12038-50. 

The production of sulfur and sulfur dioxide serves mainly for the purpose of sulfuric acid production. Sulfur is obtained from the desulfurization of natural gas or fuels, from sulfidic ores (e.g., FeS2, CU2S, or ZnS), or from natural reservoirs of elemental sulfur. The production of sulfur from natural reservoirs is carried out by either direct mining or extraction of sulfur from the ground by hot water injection (Frasch process). The further processing of elemental sulfur to sulfuric acid is treated as a process example in this book (Section 6.3). 

Adsorption process has been widely used in many chemical and related industries, such as the separation of hydrocarbon mixtures, the desulfurization of natural gas, and the removal of trace impurities in fine chemical production. Most of the adsorption researches in the past are focused on the experimental measurement of the breakthrough curve for studying the dynamics. The conventional model used for the adsorption process is based on one-dimensional or two-dimensional dispersion, in which the adsorbate flow is either simplified or computed by using computational fluid dynamics (CFD), and the distribution of adsorbate concentration is obtained by adding dispersion term to the adsorption equation with unknown turbulent mass dififusivity D(. Nevertheless, the usual way to find the D, is either by employing empirical correlation obtained from inert tracer experiment or by guessing a Schmidt number applied to the whole process. As stated in Chap. 3, such empirical method is unreliable and lacking theoretical basis. 

Zeolites a variety of crystalline silicates with pore diameters between 0.3 and 1 nm dehydration of gases, dehydration of liquids (e.g. alcohol), n-paraffins from iso-paraffins, CO2 removal from natural gas, desulfurization of natural gas and other streams, fructose/glucose separation, sulfur compounds from organics, N2/O2 separation very widely used... 

Molecular sieves have also found application for desulfurization of natural-gas feed to ammonia plants. Removal of all types of sulfur compounds ahead of these plants is desirable because sulfur acts as a temporary poi.son to steam-hydrocarbon reforming catalysts and a permanent poison to expensive low-temperature shift conversion catalysts. An installation employing a standard dual bed adsorption system has been described by Lee and Collins (1968). The authors also describe comparative tests of a molecular sieve and a commercial grade of impregnated activated carbon in a dual-bed mobile pilot unit. The test results indicated that the molecular sieve could treat 2 to 4 times as much gas per unit volume of adsorbent as the carbon. The commercial plant consistently provided gas to the primary reformer containing less than 0.3 ppm (vol) peak total sulfur from a feed gas averaging about 0.6 ppm... 

The conversion of natural gas to methanol via syngas is a widely used industrial process. A typical conventional process includes desulfurization of natural gas, steam reforming, methanol synthesis and purification by distillation. Steam reforming of natural is an endothermic reaction and operates at high temperatures (reformed gas effluent at about 800880°C). Methanol synthesis from syn is an exothermic reaction and operates at 200300°C. Heat integration and recovery is an important feature of the process. The trend in methanol production has been toward larger capacity and improved energy efficiency. 

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