Sulfur Retention Research Articles

CFD modeling of oxy-coal combustion in circulating fluidized bed

Based on the Computational Fluid Dynamics (CFD) method, the previously established and validated 2-dimensional model was employed to predict the oxy-coal combustion processes in a 50 kW circulating fluidized bed (CFB) at Southeast University, China. The simulated processes of coal conversion in our CFB combustion system included particle drying, dry coal devolatilization, volatile combustion, char combustion, char gasification and SO 2 emission. The effects of combustion atmospheres, including air (21% O 2/79% N 2) and oxygen/recycled flue gas (O 2/RFG) atmosphere with different O 2 concentration (from 21% to 40%), were investigated on distributions of solid volume fraction, temperature and gas concentration in the riser. During combustion of Xuzhou bituminous coal in O 2/RFG modes with different O 2 concentrations referred to above, about 70% volume fraction of CO 2 were achieved in the wet flue gas with more than 25% volume fraction of H 2O. The rates of char gasification by CO 2 and H 2O in 30% O 2/70% RFG atmosphere were obviously higher than that in air. However, compared to air combustion, CO concentration in the dense zone in 30% O 2/70% RFG atmosphere was lower because high concentration of H 2O accelerated CO combustion. Both indirect and direct desulfurization mechanisms were considered for sulfur retention by limestone and the corresponding overall reaction rates were calculated statistically. With increase in O 2 inlet concentration gaseous pollutant SO 2 was enriched.

Experimental Study on the Characteristics of Self-Desulfurization during Sugarcane Leaf Combustion in a Circulating Fluidized Bed

During biomass combustion, the SO2 emission would still be a problem in some cases, although the average sulfur content is relatively lower than that of coal and other fossil fuels. In this work, the characteristics of self-desulfurization during sugarcane leaf combustion in a circulating fluidized bed were experimentally investigated. First, a laboratory fixed-bed reactor was used to study how the char particles take part in the self-desulfurization process. It was observed that SO2 can be largely captured by char in the temperature range of 700–900 °C. Most of the captured sulfur was incorporated with organic char matrix rather than directly retained by inherent alkali and alkaline-earth matters in the form of inorganic salts. During char combustion, substantial amounts of the captured sulfur could be retained in the ash, which was mainly limited by the alkali and alkali-earth matters available. At higher temperatures (>800 °C), the sulfur retention reduced, mainly because the alkali and alkali-earth ma...

Mechanism of SO2 adsorption and desorption on commercial activated coke

We used commercial activated coke (AC) as adsorbent and fixed-bed, FTIR, N2 adsorption, ion chromatograph as research methods to study the SO2 removal mechanism in the presence of O2 and H2O and adsorbate (H2SO4) desorption mechanism by combined regeneration. The results showed that AC saturation sulfur retention (52.6 mg/g) in SO2+O2+H2O atmosphere was 4.6 times as much as that (11.4 mg/g) in SO2+O2 atmosphere and 5.0 times as much as that (10.6 mg/g) in SO2+O2 atmosphere at 90 °C. O2 and H2O were necessary in AC desulfurization process. Reaction of SO3 and H2O (g) and condensation of sulfuric acid vapor were the dynamic of AC desulfurization process. Water vapor blowing in combined regeneration inhibited the reaction between H2SO4 and carbon, and consequently reduced the chemical lost of carbon. AC cumulative quality loss (53.6%) of five-times in C-R was still less than that (62.4%) of three-times in H-R. Water vapor blowing inhibited reactivation effect, as a result reducing the changes of AC pore structure and surface functional groups. Adsorbate H2SO4 generated in desulfurization evaporated to sulfuric acid vapor due to the high temperature in regeneration and was carried out by water vapor.

Influencing of Ca-Based Sorbent on the Sulfur Retention

Ca-based sorbents has good performance on retening SO2 during coal combustion. In this paper, the effect of Ca/S molar ratio, coal size, combustion temperature and pretreatment time of the materials on sulfur-retention efficiency has been investigated by the method of orthogonal experiment. The work shown that the sulfur-retention is promoted greatly as Ca/S molar ratio of Ca-based agent increased. Simultaneously, the optimum experiment reveals that CaO as sulfur-fixing agent, Ca/S molar ratio 2.0, combustion temperature of 900°C, coal particle size of smaller than 180 mesh and pretreatment for 30min could attain the best results.

Spatial variation in response to ‘reduced input’ spray programs for powdery mildew and botrytis identified through whole-of-block experimentation

Background and Aims: Previous work has highlighted the utility of the whole-of-block approach to viticultural experimentation. Here, we use this approach as a means of evaluating alternative spray programs for managing two economically important grapevine diseases at commercial scale. Methods and Results: Two experiments were conducted in vineyards in the Coal River and Rokeby districts of Tasmania. The first, carried out in a 4.5 ha vineyard planted to Vitis vinifera L. cv. Pinot Noir, sought to evaluate fungicide programs for control of powdery mildew ( Erysiphe necator ), in particular with a view to reducing the amount of sulphur applied in organic production systems. The second sought to evaluate the benefit (if any) of changing the time of fungicide application from flowering to pre-bunch closure for the control of botrytis bunch rot ( Botrytis cinerea ) in a 2.4 ha Chardonnay vineyard. In both cases, treatments were applied to a whole-of-block experimental design using commercial spray equipment. Disease severity and the response to the various spray treatments, was spatially variable and related to topographic variation. Botrytis severity was also related to vine vigour. The powdery mildew results supported the retention of sulphur in organic spray programs, while Switch® (Syngenta Group, Basel, Switzerland) applied at pre-bunch closure in the botrytis experiment reduced disease severity relative to the application at flowering. Spatial variation in the response to the latter treatment, when examined four times pre-harvest, suggested that secondary spread may not have been an important mechanism for increasing disease severity over time. Conclusions: Consistent with the other work described in this series of papers, we conclude that the whole-of-block experimental approach offers both researchers and vineyard managers a means of acquiring more useful information than would be obtained from a conventional plot-based approach. Significance of the Study: This study highlights the value of collecting spatially distributed data as a means of better understanding the incidence, spread, progression and control of fungal grapevine diseases. As such, it provides a new application for this experimental approach, which enables spatial variability to be used as an experimental tool.

Characterization of a limestone in a batch fluidized bed reactor for sulfur retention under oxy-fuel operating conditions

CO 2 and SO 2 are some of the main polluting gases emitted into atmosphere in combustion processes using fossil fuel for energy production. The former is one of the major contributors to build-up the greenhouse effect implicated in global climate change and the latter produces acid rain. Oxy-fuel combustion is a technology, which consists in burning the fuel with a mix of pure O 2 and recirculated CO 2. With this technology the CO 2 concentration in the flue gas may be enriched up to 95%, becoming possible an easy CO 2 recovery. In addition, oxy-fuel combustion in fluidized beds allows in situ desulfurization of combustion gases by supplying calcium based sorbent. In this work, the effect of the principal operation variables affecting the sulfation reaction rate in fluidized bed reactors (temperature, CO 2 partial pressure, SO 2 concentration and particle size) under typical oxy-fuel combustion conditions have been analyzed in a batch fluidized bed reactor using a limestone as sorbent. It has been observed that sulfur retention can be carried out by direct sulfation of the CaCO 3 or by sulfation of the CaO (indirect sulfation) formed by CaCO 3 calcination. Direct sulfation and indirect sulfation operating conditions depended on the temperature and CO 2 partial pressure. The rate of direct sulfation rose with temperature and the rate of indirect sulfation for long reaction times decreased with temperature. An increase in the CO 2 partial pressure had a negative influence on the sulfation conversion reached by the limestone due to a higher temperature was needed to work in conditions of indirect sulfation. Thus, it is expected that the optimum temperature for sulfur retention in oxy-fuel combustion in fluidized bed reactors be about 925–950 °C. Sulfation reaction rate rose with decreasing sorbent particle size and increasing SO 2 concentration.

Identification of New Strawberry Sulfur Volatiles and Changes during Maturation

Two Florida strawberry cultivars, 'Strawberry Festival' and 'Florida Radiance', were harvested at five fruit developmental stages (white, half red, three-quarter red, full ripe, and overripe) at four harvest dates. A static headspace solid-phase microextraction (SPME) sampling technique coupled with gas chromatography (GC) using pulsed flame photometric detection (PFPD) was employed to measure 16 sulfur volatiles in these strawberries. A total of 7 sulfur volatiles have been previously reported, and 9 are reported for the first time in strawberries. Newly identified sulfur volatiles include methyl thiopropionate, ethyl thiobutanoate, methyl thiohexanoate, methyl (methylthio)acetate, ethyl (methylthio)acetate, methyl 2-(methylthio)butyrate, methyl 3-(methylthio)propionate, ethyl 3-(methylthio)propionate, and methyl thiooctanoate. Identifications were based on matching sulfur peak linear retention indexes (LRIs) of unknowns with authentic standards and gas chromatography-mass spectrometry (GC-MS) data. Concentrations were determined using both internal and external standards. Most sulfur volatiles increased with increasing maturity, with only concentrations of hydrogen sulfide and methanethiol remaining relatively consistent at all five stages. At the white and half red stages, most sulfur volatiles consisted of various alkyl sulfides. At three-quarter red (commercial ripe), full ripe, and overripe stages, the majority of sulfur volatiles consisted of sulfur esters. Most sulfur volatiles increased dramatically between the commercial ripe, full ripe, and overripe stages, increasing as much as 100% between full ripe and overripe. Principal component analysis indicated that sulfur volatiles could be used to distinguish overripe from full ripe and commercial ripe berries.

Electrogeneration of (Z)-α-aroyloxy-β-aroylthiostilbenes and (Z)-4,5-diaryl-2-arylimino-1,3-oxathioles by cathodic reduction of monothiobenzils in the presence of electrophilic reagents. Computational B3LYP and RI-MP2 study on the relative stability of oxathiole compounds

Electrochemical reductions of monothiobenzils in the presence of either aroyl or carbonimidoyl dichlorides were carried out, yielding products with sulfur retention. Electrolyses in the presence of aroyl chlorides led to previously unknown (Z)-α-aroyloxy-β-aroylthiostilbenes in high to quantitative yields, whereas reactions in the presence of arylcarbonimidoyl dichlorides provided novel 4,5-diaryl-2-arylimino-1,3-oxathioles in fair to high yields. The molecular structures of (Z)-α-benzoyloxy-β-benzoylthio-4,4′-dimethylstilbene and (Z)-2-(2,4-dichlorophenylimino)-4,5-diphenyl-1,3-oxathiole were determined by X-ray crystallography. Also, ab initio HF, density functional B3LYP, and Moller–Plesset RI-MP2 procedures were applied to oxathiole compounds revealing that (Z)-isomers are more stable than (E)-isomers and that both isomers are separated by a relatively low activation barrier.

Sulphur transformation during pyrolysis of an Australian lignite

Transformation of various sulphur forms, including inherent and added pyrite, sulphates (CaSO 4 and FeSO 4) and organic sulphur, during pyrolysis of an Australian lignite was studied using TGA, TGA-MS and a fixed bed reactor, supplemented by sulphur form analysis. It was shown that hydrogen sulphide (H 2S) and a small quantity of sulphur dioxide (SO 2) were released during the pyrolysis of the pyrite-lignite blend. However, only SO 2 was detected during the pyrolysis of the lignite with high pyrite content. Inorganic matter was found to help retaining some of the inorganic sulphur, including pyrite, in the char. Inherent sulphates decomposed at much lower temperatures than the added sulphates, releasing SO 2 rather than H 2S. The inherent sulphates in the lignite were dominated by iron sulphates which started to decompose and release SO 2 at around 500 K and all sulphate had been decomposed at 1073 K. The retention of organic sulphur in the high organic sulphur lignite was higher than in its acid washed lignite sample, due to the interaction between inherent inorganic matter with the organic sulphur retaining the organic sulphur in the solid phase. SO 2 was the only sulphur gas produced during pyrolysis of acid washed lignite. A comprehensive mechanism of sulphur transformation during pyrolysis of lignite was proposed.

Modelling boreal lake catchment response to anthropogenic acid deposition

A dynamic hydrogeochemical model of water acidification (MAGIC: Model of Acidification of Groundwater in Catchments) was applied to two catchments with contrasting hydrological influences in the Athabasca Oil Sands Region of Alberta to predict catchment response to elevated levels of acidic deposition. Key processes that determine catchment response to atmospheric deposition, including groundwater base cation inputs and retention of sulphur (S) in peatland complexes were parameterized in the model. Although deposition of S and nitrogen (N) in the region has increased over the last 40 years, levels are low at the study sites relative to impacted areas of eastern North America. Model forecasts for the period 2005–2100 were run under constant 2005 deposition levels (base case) and at acid deposition double this level. Simulated past and future soil base saturation was constant over the course of the 200 year (1900–2100) modelled period. At the lake with high charge balance acid neutralizing capacity (ANCCB), where large base cation sources dominate lake chemistry, little change in surface water chemistry was predicted under either forecast scenario. Under the double acid forecast scenario at the low ANCCB lake, simulated lake ANCCB decreased in response to elevated S deposition, but the magnitude of decrease was comparable to the range in observational data. The simulations suggest limited risk of acidification, primarily due to S retention in the catchments, but the potential for drought-induced episodic depression of ANCCB may be important on this landscape.

Modelling catchment response to acid deposition: a regional dual application of the MAGIC model to soils and lakes in the Athabasca Oil Sands Region, Alberta

The effects-based acid emissions management framework (EMF) for determining the need for emission control policies in the Athabasca Oil Sands Region, Canada is dependent on model simulations of future soil and surface water chemistry. An approach for regional application of the Model of Acidification of Groundwater in Catchments (MAGIC) was developed that addresses the differential sensitivity of forest soils and lakes. The approach used was a dual application wherein a plot-scale calibration to forest soils and a catchment-based calibration to lake chemistry were used to account for poorly understood hydrologic connections between uplands and lakes, key processes including sulphur (S) and nitrogen (N) retention as well as groundwater sources of base cations to the lakes. The regional application was carried out at 50 lake catchments currently monitored for response to acid deposition. Simulated forest soil chemistry (modelled at 28 catchments) exhibited small changes in base saturation under future conditions of elevated acid deposition, while in general molar BC:Al exhibited considerable change but remained well above critical chemical limits used to protect acid-sensitive forest soils. Similarly, simulations of charge balance acid neutralizing capacity (ANCCB) for the lakes suggested very small decreases since industrialization, and forecast projections under acid deposition double the current level suggested that only one lake will reach the critical threshold for ANCCB (75 μeq L–1) specified by the EMF. There is limited potential for acidification impacts at the study sites.

Immune system stimulation of growing pigs does not alter apparent ileal amino acid digestibility but reduces the ratio between whole body nitrogen and sulfur retention

Immune system stimulation (ISS) can cause morphological and physiological changes in the gastrointestinal tract and impact nutrient utilization in pigs. Apparent ileal digestibility (AID) of sulfur amino acids (SAA) and whole body nitrogen (N) to sulfur (S) balance ratios (N/S-balance) were measured to investigate the impact of ISS and SAA intake on SAA digestibility and utilization in growing pigs. Thirty-six barrows (initial BW 21.5 ± 3.5 kg) were fed 800 g/day of SAA-limiting diets that supplied 1.1, 2.1 or 3.2 g/day of SAA (L1, L2 and L3, respectively). Following adaptation, pigs were injected intramuscularly, with either saline (ISS−; 4 pigs at each SAA intake level) or increasing amounts of Escherichia coli lipopolysaccharide (LPS) (ISS+; 8 pigs at each SAA intake level), while measuring whole body N and S balances. At the end of the balance period, pigs were euthanized and digesta were collected from the distal 1.5 m of small intestine for measuring AID (%) of amino acids and energy. The AID of energy and amino acids were not affected by ISS. Whole body N and S retention increased with SAA intake ( P < 0.01), while only N retention was reduced by ISS ( P < 0.05). Whole body N/S-balance was reduced as SAA intake decreased; ISS further reduced the N/S-balance ( P < 0.03), indicating an increase in whole body non-protein SAA pool size due to ISS. In conclusion, ISS per se does not change the AID of amino acids and energy but alters the partitioning of SAA in favor of non-protein body stores in growing pigs.

Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging

Evolution of flight in maniraptoran dinosaurs is marked by the acquisition of distinct avian characters, such as feathers, as seen in Archaeopteryx from the Solnhofen limestone. These rare fossils were pivotal in confirming the dinosauria-avian lineage. One of the key derived avian characters is the possession of feathers, details of which were remarkably preserved in the Lagerstätte environment. These structures were previously simply assumed to be impressions; however, a detailed chemical analysis has, until now, never been completed on any Archaeopteryx specimen. Here we present chemical imaging via synchrotron rapid scanning X-ray fluorescence (SRS-XRF) of the Thermopolis Archaeopteryx, which shows that portions of the feathers are not impressions but are in fact remnant body fossil structures, maintaining elemental compositions that are completely different from the embedding geological matrix. Our results indicate phosphorous and sulfur retention in soft tissue as well as trace metal (Zn and Cu) retention in bone. Other previously unknown chemical details of Archaeopteryx are also revealed in this study including: bone chemistry, taphonomy (fossilization process), and curation artifacts. SRS-XRF represents a major advancement in the study of the life chemistry and fossilization processes of Archaeopteryx and other extinct organisms because it is now practical to image the chemistry of large specimens rapidly at concentration levels of parts per million. This technique has wider application to the archaeological, forensic, and biological sciences, enabling the mapping of "unseen" compounds critical to understanding biological structures, modes of preservation, and environmental context.

Effects of Indigenous and Added Minerals on Transformation of Organic and Inorganic Sulfur in Density Separated Coal Fractions during CO2-Pyrolysis†

The present paper was addressed toward the impacts of indigenous and added minerals on the organic and inorganic sulfur transformations during CO2-pyrolysis in a fixed-bed reactor at a temperature range of 400−800 °C. A Chinese bituminous coal was separated into three density fractions using the float-sink method: light (<1.4 g/cm3), medium (1.4−2.0 g/cm3), and heavy (>2.0 g/cm3). The sulfur retention of the three coal fractions was characterized in detail to study the influence of indigenous minerals on organic and inorganic sulfur transformation. Moreover, the role of added minerals was investigated by adding NaCl and kaolinite. The results indicated that indigenous minerals promoted the sulfur retention in coal char, especially in C>2.0, but had little effect on the decomposition of inorganic sulfur. Meanwhile, it was found that the added minerals also increased the sulfur retention. NaCl had a remarkable effect on sulfur retention at a low temperature range but appeared to have little capacity of sulfur retention due to the volatilization of itself at high temperatures above 700 °C. As for kaolinite, it was observed that there was an indistinct ability to retain sulfur during CO2-pyrolysis in our study. In comparison with added minerals, indigenous minerals had more significant effects on sulfur transformation because they were inherently embedded in the organic matrix of coal, while added minerals were physically dispersed within coal.

Validation of a FBC model for co-firing of hazelnut shell with lignite against experimental data

Abstract Performance of a comprehensive system model extended for modelling of co-firing of lignite and biomass was assessed by applying it to METU 0.3 MW t Atmospheric Bubbling Fluidized Bed Combustor co-firing lignite with hazelnut shell and validating its predictions against on-line temperature and concentration measurements of O 2 , CO 2 , CO, SO 2 and NO along the same test rig fired with lignite only, lignite with limestone addition and lignite with biomass and limestone addition. The system model accounts for hydrodynamics; volatiles release and combustion, char combustion, particle size distribution for lignite and biomass; entrainment; elutriation; sulfur retention and NO formation and reduction, and is based on conservation equations for energy and chemical species. Special attention was paid to different devolatilization characteristics of lignite and biomass. A volatiles release model based on a particle movement model and a devolatilization kinetic model were incorporated into the system model separately for both fuels. Kinetic parameters for devolatilization were determined via thermogravimetric analysis. Predicted and measured temperatures and concentrations of gaseous species along the combustor were found to be in good agreement. Introduction of biomass to lignite was found to decrease SO 2 emissions but did not affect NO emissions significantly. The system model proposed in this study proves to be a useful tool in qualitatively and quantitatively simulating the processes taking place in a bubbling fluidized bed combustor burning lignite with biomass.

Sulfur evolution from coal combustion in O 2/CO 2 mixture

O 2/CO 2 coal combustion technology is considered as one of the most promising technologies for CO 2 sequestration due to its economical advantages and technical feasibility. It is significant to study the sulfur transfer behavior of coal in O 2/CO 2 atmosphere for organizing combustion properly and controlling SO 2 emission effectively. To clarify the effect of atmosphere on the sulfur transfer behavior, thermogravimetry coupled with Fourier Transform Infrared (TG-FTIR) system was employed to study the formation behavior of sulfur-containing gas species from Xuzhou bituminous coal pyrolysis in CO 2 atmosphere compared with that in N 2 atmosphere. Also the SO 2 formation behaviors during Xuzhou bituminous coal combustion in O 2/N 2 and O 2/CO 2 atmospheres were investigated. Results show that COS is preferentially formed during the coal pyrolysis process in CO 2 atmosphere rather than in N 2 atmosphere. When temperature is above 1000 K, sulfate in the CO 2 atmosphere begins to decompose due to the reduction effect of CO, which comes from the CO 2 gasification. During coal combustion process, replacing N 2 with CO 2 enhances the SO 2 releasing rate. SO 2 emission increases first and then decreases as O 2 fraction increases in the O 2/CO 2 mixture. XPS result of the ash after combustion indicates that higher O 2 concentration elevates the sulfur retention ability of the mineral matter in the coal.

Transformation of organic and inorganic sulphur in a lignite during pyrolysis: Influence of inherent and added inorganic matter

The transformation of organic and inorganic sulphur during pyrolysis of a Western Australian lignite has been studied using several complimentary techniques. The lignite contains high moisture, oxygen, volatile matter, organic sulphur and inherent inorganic matter. FTIR and solid state 13C TOSS NMR spectroscopic studies revealed that the high oxygen content is attributed to the oxygenated functional groups, which is saturated with organically bonded inherent inorganic matter. Sodium and chlorine are the dominant inorganic matter and present in the form of sodium chloride. TGA-MS studies of the raw lignite showed that SO 2 is the dominant sulphur-bearing gases evolved during the pyrolysis of the raw lignite. The effect of inherent and added inorganics was studied by comparing the amounts of various forms of sulphur retained in the chars of the raw lignite, the acid washed lignite and the acid washed lignite doped with sodium and kaolinite following pyrolysis in a fixed-bed reactor in nitrogen. Inherent inorganic matter was shown to reduce the decomposition of organic sulphur but has little effect on the decomposition of inorganic sulphur. Sodium helps the retention of sulphur in the chars between 400 and 500 °C while kaolinite has a better ability to retain sulphur above 600 °C.

SULFUR FORMATION AND RECOVERY IN A THIOSULFATE‐OXIDIZING BIOREACTOR

This work describes the design and performance of a thiosulfate‐oxidizing bioreactor that allowed high elemental sulfur production and recovery efficiency. The reactor system, referred to as a Supernatant‐Recycling Settler Bioreactor (SRSB), consisted of a cylindrical upflow reactor and a separate aeration vessel. The reactor was equipped with an internal settler and packing material (structured corrugated PVC sheets) to facilitate both cell retention and the settling of the formed elemental sulfur. The supernatant from the reactor was continuously recirculated through the aerator. An inlet thiosulfate concentration of 100 mmol l−1 was used. The reactor system was fed with 89 mmol l−1 d−1 thiosulfate reaching 98 to 100% thiosulfate conversion with an elemental sulfur yield of 77%. Ninety‐three percent of the produced sulfur was harvested from the bottom of the reactor as sulfur sludge. The dry sulfur sludge contained 87% elemental sulfur. The inclusion of an internal settler and packing material in the reactor system resulted in an effective retention of sulfur and biomass inside the bioreactor, preventing the oxidation of thiosulfate and elemental sulfur to sulfate in the aerator and, therefore, improving the efficiency of elemental sulfur formation and recovery.

Sulfur Abatement in Pyrolysis of Straw Pellets

A batch-type reactor was used to study the sulfur release from pellets made of Danish wheat straw during inert conditions. In addition, two means of sulfur abatement were investigated, the use of calcium-based additives for sulfur retention and the use of nonthermal plasma (NTP) for the treatment of the devolatilized products. The results were interpreted by quantifying the releases of hydrogen sulfide (H 2S) and carbonyl sulfide (COS) to the gas phase for the pyrolysis temperatures of 400−800 °C. In experiments where additives were used, straw was mixed and pelletized with either calcium oxide (CaO) or calcium hydroxide [Ca(OH) 2] at different calcium/sulfur ratios. The effect of additives on the sulfur release was difficult to assess by solely investigating the gaseous products. However, a comparison of the sulfur content in the starting material and the char residues after pyrolysis showed evidence of minor sulfur retention. The nonthermal plasma reactor system was set up to process the produced gas either before or after the removal of the liquid fraction from the devolatilized products. Furthermore, carbon dioxide was mixed with the nitrogen carrier gas to achieve a more complex gas composition for the nonthermal plasma. For comparative reasons, some preliminary experiments were performed to study the removal efficiency of H 2S in pure nitrogen. The removal efficiency for sulfur under the effect of nonthermal plasma in pure N 2 increased with an increasing H 2S concentration and plasma power. The highest registered removal efficiency was close to 96%. The removal efficiency of H 2S in the pyrolysis experiments was highest at a pyrolysis temperature of 400 °C, with the nonthermal plasma reactor placed downstream of liquid removal. At this configuration, 86% of H 2S was removed from the devolatilized products. The best plasma reactor placement was proved to be downstream of liquid removal for both H 2S and COS. Increasing the CO 2 amount in the carrier gas has improved the removal efficiency of H 2S at the cost of increased COS formation.

Synthesis and Activity Comparison of Copper-Incorporated MCM-41-Type Sorbents Prepared by One-Pot and Impregnation Procedures for H2S Removal

In the present study, novel copper-incorporated MCM-41-type high-surface-area mesoporous materials were synthesized following a direct hydrothermal synthesis method and also by the impregnation of copper into the mesopores of the pre-synthesized MCM-41 structure. XRD results indicated the formation of a CuO phase within the MCM-41 structure. Sharp H2S breakthrough curves, quite high sorption rate parameters, and high sulfur retention capacities were obtained in high-temperature removal of H2S using these copper-incorporated mesoporous materials. XRD patterns of the sulfided products indicated the formation of a Cu1.81S phase within the MCM-41 structure. A deactivation model gave good predictions of the experimental H2S breakthrough data.