Degree Of Desulfurization Research Articles

Valorization of Industrial Brine Sludge Waste for Augmented Spray Dry Scrubbing of SO₂ using Hygroscopic Additives

Detailed experiments were conducted using a laboratory-scale spray dryer under controlled conditions to investigate the effects of highly hygroscopic additives on the performance of hydrated lime (Ca(OH)2) in spray dry scrubbing (SDS) of sulfur dioxide (SO2). The experiment involved the preparation of hydrated lime sorbent from industrial brine sludge waste (IBSW) as the starting material. The evaluated additives included sodium hydroxide, ammonium nitrate, ammonium chloride, sodium chloride, and urea. The additives were chosen based on their hygroscopicity, as it is understood that the degree of desulfurization and sorbent conversion in an SDS is significantly enhanced in the prolonged liquid phase. Experiments were conducted at a constant inlet flue gas temperature of 140°C, sorbent particle size of -45μm, while the calcium to sulfur (Ca:S) ratio was varied in the range of 1.0 - 2.5. Slurry with 10 wt.% Ca(OH)2 was used while varying the additive concentration from 2 to 8 wt.%. The experimental findings revealed that all the investigated additives, except urea, promoted the removal efficiency of SO2 above baseline. Sodium hydroxide was the best-performing additive achieving 92.06% SO2 removal efficiency and a calcium conversion of 54.59%. Fourier-transform infrared spectroscopy (FTIR) analysis showed traces of additives present in the sulfation products. Similarly, X-Ray diffraction (XRD) analysis on the final product showed the presence of desulfurization products and the respective additive compounds. Scanning electron microscopy (SEM) depicted reaction products particles as course, irregular, and deformed.

A comprehensive study on the rheological properties of desulfurized rubberized asphalt and establishment of micro-scale mechanical models

Recently, understanding the complex relationship between the mechanical properties and material characteristics of desulfurized rubber asphalt has received significant research attention. In this study, the rheological properties of rubber asphalt prepared by three kinds of desulfurized rubber powder are analyzed, and the mechanical response of rubber asphalt mixture is predicted using various mathematical models. Firstly, the rheological properties of desulfurized rubber asphalt are assessed through multiple stress creep recovery test, linear amplitude scanning test, and low-temperature creep test. The results indicate that the high-temperature performance index of desulfurized rubber asphalt is highly sensitive to the degree of desulfurization. As the degree of desulfurization of the rubber powder increases, the fatigue damage rate of asphalt gradually decreases, leading to an increase in the fatigue life. Notably, the difference between the m-critical temperature and stiffness-critical temperature (ΔTc) for only ML40MA does not exceed the threshold value, indicating that it has the best low-temperature cracking resistance. Additionally, the swelling capacity of desulfurized rubber powder in asphalt is better than that of ordinary rubber powder. Finally, the comprehensive performance of desulfurized rubber asphalt is characterized based on the gray correlation method. The gray correlation coefficient of ML60MA is 0.78, which is higher than that of ML40MA and ML80MA, indicating its best overall performance.

Rheological and adhesive improvements of terminal blend rubberized asphalt via fumed silica nanoparticle modification

Due to the high degree of desulfurization and depolymerization of crumb rubber (CR) particles in terminal blend rubberized asphalt (TBRA), their elasticity and adhesive performance are insufficient. To address this, the study utilized low-cost fume silica nanoparticles (FSNPs) to enhance the elasticity and adhesive properties. TBRA binders with varying CR contents (30 %, 40 %, 50 %) were modified using different dosages of FSNPs (2 %, 4 %, 6 %). The microstructure of FSNPs was examined through TEM and SEM. Using a dynamic shear rheometer (DSR) test, contact angle test, and atomic force microscope (AFM) test, the effects of FSNPs on the rheological properties, surface energy, and adhesive properties of TBRA binders were evaluated. The results showed significant improvements in the deformation resistance and elasticity of the TBRA binders modified with FSNPs. This is attributed to the branched network structure of FSNPs, which notably enhances the binder's cohesion, thereby strengthening its resistance to shear deformation and improving elasticity. FSNPs effectively reduce the moisture sensitivity of TBRA, due to the hydrophilic hydroxyl groups on FSNPs being replaced by hydrophobic methyl groups (-CH3). The inadequate bonding performance of TBRA can be attributed to the high levels of extensively depolymerized and desulfurized CR particles, which reduce the cohesiveness of the binder. The addition of FSNPs, although it lowers the surface energy of TBRA binders, significantly enhances their cohesiveness due to the branched network structure, thereby improving their bond performance. AFM results indicate that FSNPs enhance the adhesive strength of the TBRA binder surface due to their high specific surface area, which provides more van der Waals forces and electrostatic interactions. For economic efficiency, an addition of 4 % is recommended for TB30, and 2 % for TB40 and TB50. At these specified concentrations, the bond strength of the TBRA binder can be increased by 45–55 %.

Development of eco-friendly and high-content rubberized asphalt modified by waste cooking oil desulfurized crumb rubber and waste crumb rubber

To conserve non-renewable petroleum-based asphalt resources and address the limitations of incorporating high-content waste crumb rubber (CR) in conventional crumb rubber modified asphalt (CRMA), this study examines the feasibility of utilizing waste cooking oil desulfurized crumb rubber (ODR) in conjunction with CR to prepare high-content rubberized asphalt (HCRA). The basic, chemical, rheological, and asphalt-aggregate adhesion properties of HCRA, both with and without a small quantity of styrene-butadiene-styrene (SBS) copolymer modifier, were evaluated using infrared spectroscopy (FTIR), dynamic shear rheometer (DSR), bending beam rheometer (BBR), asphalt-aggregate pull-off test, contact angle test, and atomic force microscopy (AFM). The results showed that the modification involving ODR and CR primarily constitutes a physical process, rather than a chemical reaction, as evidenced by the lack of new functional groups. Similarly, the addition of an SBS modifier predominantly results in physical modifications accompanied by minor chemical interactions. The improved desulfurization degree of ODR diminishes the elastic stiffening effect of CR on the matrix asphalt at the high-temperature (low-frequency) domain and reduces adhesion properties between HCRA and aggregates, while enhancing the flexibility of HCRA at the low-temperature (high-frequency) domain. The inclusion of a small quantity of SBS modifier allows HCRA to demonstrate high-temperature performance and adhesion properties on par with CRMA, alongside superior low-temperature stress relaxation, phase stability, storage stability, and water damage resistance. These attributes indicate that the HCRA with a small quantity of SBS modifier has a broader service temperature range compared to CRMA. This study achieves approximately 33.3 % replacement of asphalt materials while preserving the performance of rubberized asphalt.

Correlation between Thermodynamic Studies and Experimental Process for Roasting Cobalt-Bearing Pyrite

Cobalt is a critical metal widely distributed in nature, but cobalt ore has hardly been found as an independent mineral. Cobalt-bearing pyrite tailings separated from iron ore is one of the resources for recovering cobalt. In the following study, roasting is carried out to oxidize cobalt-bearing pyrite tailings for preparing and recovering the cobalt by acid leaching. The further aim of the research is to determine and control the optimal technological regime for roasting by using thermodynamic modeling. The phase transition in Fe–S–O and Co–S–O systems and its mechanism are analyzed under the partial pressure of oxygen and sulfur dioxide at constant temperatures. Thermodynamic modeling proves that iron and cobalt sulfides can be intensively oxidized at a relatively high temperature (>900 °C) under an atmosphere of logp(O2) > −5, leading to the formation of SO2 (logp(SO2) < 0). The results of the roasting experiment indicate 98% desulfurization degree upon holding for about 4–5 h and at > 1000 °C. Based on these thermodynamic modeling and experimental results, the roasting of cobalt containing pyrite can be optimized with substantial productivity with regard to the metal oxide and cobalt thereof. Oxidative roasting also allows the elimination of environmentally hazardous gases such as sulfur during the process.

Novel titanium silicon micro-mesoporous composites via nano-assembly strategy for efficient hydrodesulfurization of dibenzothiophene

A unique hierarchical TS-1/FDU-12 (TF) micro-mesoporous composite was synthesized by nano-assembly method, and was used as an excellent support for high-efficiency hydrodesulfurization (HDS) catalyst (NiMo/TF) of dibenzothiophene (DBT). The introduction of TS-1 nanocrystals provided more S vacancies and more acidic sites to the NiMo/TF catalysts, and showed no effect on the highly ordered three-dimensional structure of the composites, leading to excellent HDS performance of NiMo/TF catalysts. The superior acidity of NiMo/TF favored the HYD pathway of DBT, resulting in improved DBT HDS activity with up to 98.0 % desulfurization degree. In addition, NiMo/TF presented an optimal reaction rate constant (kHDS) of 5.9 × 10-4 mol g-1 h−1, a turnover frequency (TOF) value of 1.6 h−1 and a low activation energy (Ea) of 47.7 kJ mol−1, which are due to the synergistic effect of large specific surface area, appropriate pore size, abundant Brønsted & Lewis acidic sites, suitable MSI, high sulfurization degree and highly dispersed MoS2 active phases.

CuY@NiAl-Layered double oxides bi-functional composites for “Catalytic–Adsorptive” removal of carbonyl sulfide

Carbonyl sulfide (COS) removal processes, typically containing catalytic hydrolysis and subsequent capture of hydrogen sulfide (H2S) generated, are energy-intensive and of high complexity. Bi-functional materials with the capability for synergistic catalytic conversion of COS and subsequent adsorption capture of H2S can enable effective removal of COS at low energy cost. Here, we report the development of a bi-functional CuY@NiAl-LDO composite material with integrated catalytic conversion of COS and adsorptive separation of H2S with high efficiency and stability. Fundamental material characterizations elucidate that the CuY@NiAl-LDO composite materials feature a core–shell structure. Coupled dynamic breakthrough experiments and DFT simulations highlight the unique synergistic “catalytic–adsorptive” effect between CuY and NiAl-LDO in the COS removal processes. Specifically, compared with the pure zeolite CuY and NiAl-LDO, the CuY@NiAl-LDO composites present significantly higher COS removal performance. The highest degree of desulfurization was observed on CuY@NiAl-LDO(46 %) at 80 °C with a breakthrough sulfur capacity of 20.57 mg-S/g and no detectable H2S in the outlet gas. In sum, this study highlights the synergistic “catalytic–adsorptive” mechanism of the bi-functional CuY@NiAl-LDO core–shell composite in desulfurization. The insights obtained may benefit chemical engineers by providing a new strategy for the development of multi-functional desulfurization materials.

Estimation of hot metal desulfurization by intermediate and final blast-furnace slag when using pellets of different basicity in blast-furnace charge

n the process of blast-furnace smelting, up to 90% of coke sulfur is captured by the iron ore charge, accumulating in hot metal in the amount that was absorbed from the gas phase. Desulphurization of cast iron occurs when it interacts first with the intermediate, and at the final stage, with the final blast-furnace slag. In this regard, it is of interest to evaluate the desulfurizing properties of the intermediate and final slag, which affect the sulfur content in hot metal. Melting mixtures of pellets of different basicity and sinter in a blast furnace leads to the formation of primary and intermediate slags of different chemical composition. When smelting hot metal in blast furnaces, mainly unfluxed pel-lets and fluxed sinter are used. In the course of the study, mixtures of sinter and pellets of different basicity were pre-pared, which ensured the production of final blast-furnace slag with a basicity of CaO/SiO2 = 1.15 units. The mixtures were reduced and melted in graphite crucibles with the smelting products filtered through a coke nozzle. The coeffi-cients of sulfur distribution between intermediate slag and hot metal obtained from iron ore charge with different basicity of sinter and pellets were determined. The lowest sulfur distribution coefficient between the intermediate slag and hot metal is observed when the basicity of the pellets is in the range of 0.5‒1.2 units. To increase the desulfurization capacity of the intermediate slag, it is advisable to use unfluxed and fluxed pellets with a basicity of 0.25 units in the blast-furnace charge and an sinter with a basicity of 1.78‒1.87 units. Studies of the kinetics of the interaction of hot metal and final blast-furnace slag have shown that the final slag provides a high degree of desulfurization of hot metal during their interaction for 1 hour or more

Influence of SBS on the Aging Properties of High-Content Terminal Blend Rubber Modified Asphalt

The goal of this study was to investigate the effect of styrene-butadiene-styrene (SBS) polymer on the aging properties of high-content terminal blend rubber modified asphalt (HCTBMA). All asphalt was tested for chemo-rheological properties using an attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR) test, temperature sweep test, frequency sweep tests, and multiple stress creep recovery (MSCR) test. According to ATR-FTIR observations, SBS can retard the oxidation effect of HCTBMA during short-term aging, but its inhibitory effect is reduced during long-term aging. Furthermore, aging aggravates the degree of desulfurization of crumb rubber in HCTBMA as the SBS content increases. Compared with HCTBMA, neat asphalt has a lower elasticity at high temperatures and a higher elasticity at low temperatures. The addition of SBS to HCTBMA improves the elasticity of the material. The elasticity of HCTBMA decreases and then increases after aging, and SBS can reduce the aging degree of HCTBMA after aging. Moreover, based on Pearson correlation analysis, the correlation between the desulfurization of rubber and the degradation of polybutadiene in HCTBMA during aging is high.

HYDROCATALYTIC PROCESSING OF FUEL OILS WITH THE USE OF NANOCATALYSTS BASED ON NICKEL AND ZINC

The article presents the results of a study of hydrocatalytic processing of two fuel oils in the presence of nanocatalytic systems in the form of oil-soluble precursors based on nickel and zinc. The process was carried out on a pilot plant for hydroprocessing with a flow reactor at a temperature of 440 ℃, a hydrogen pressure of 6 MPa, a feed space velocity of 1.0 s-1, and a hydrogen circulation ratio of 1000 nl/l. The catalyst efficiency was evaluated by changes in the material balance, in hydrogenate desulfurization degree, in 450+ °C fraction conversion degree, and by changes in density and hydrogenate refractive index. An analysis of material balances showed that the addition of nanocatalyst precursors increases the 180–350 °C fraction yield, reduces the coke yield on the fixed layer, which is a layer of ceramic balls, and reduces the 450+ °C residual fraction yield. The gas and gasoline fraction yield is slightly reduced. The analysis of hydrogenates showed a decrease in sulfur content, a decrease in density and refractive index in hydrogenates obtained during the hydroprocessing of raw materials with the addition of nanocatalyst precursors. The optimal concentrations of catalysts were experimentally determined; for nickel, the concentration is 0.1 wt %, and for zinc is 0.15 wt %. A comparison of two methods for the synthesis of nanoscale catalytic systems in raw materials was made: directly in the reaction zone in situ and outside the reaction zone ex situ. The method for synthesizing nanoscale catalytic systems outside the reaction zone makes it possible to further increase the feedstock conversion, the hydrogenate desulfurization degree, and the hydrogenate quality.

Simulation of ionic-liquid extractive purification process of thiophene and m-xylene from their mixture with n-hexane by the molecular dynamics method

This paper deals with the results of simulation of extractive purification process of model diesel fuel (the mixture of n-hexane with thiophene and m-xylene) by molecular dynamics simulation using N-methylpyrrolidinium acetate ionic liquid as an extractant. The extractive purification process was simulated for several model fuel systems with different concentrations of sulfur and aromatic containing components. The ionic liquid exhibits high extractive ability, the degrees of desulfurization and dearomatization reach 85–90 and 60[Formula: see text]wt.%, respectively. The results were proved by experimental studies of a mixture by the ionic liquid. After 1[Formula: see text]h of contact of the ionic liquid and the model mixture, the degree of purification against thiophene was 94.2[Formula: see text]wt.%.

Method for oxidative roasting of sulfide zinc concentrates in an air oxygen stream in fluidized bed furnaces

An increase in the oxygen content in the blast to a concentration of 26-28% during the firing of zinc concentrates in the KS furnaces leads to a decrease in the formation of undesirable compounds of ferrites and zinc silicates, increases the degree of desulfurization, and shortens the firing time. At the same time, it becomes possible to load concentrate with high humidity into the furnace, which will save costs for drying the raw materials. Ultimately, it leads to an increase in the complexity of raw materials, increasing the profitability of production and making the products competitive in the world market. The article is considered questions of increased efficiency of processing collective zinc concentrates without their preliminary selective division. Our developments on the processing of collective zinc concentrates are directed to that in the maximum degree to receive sulfates of zinc transferring zinc to the solution. Thermodynamic calculations show that the formation of sulfates most intensively precedes in the range of 1000-1100 °C. It is offered to carry out roasting of a collective concentrate to furnaces of the boiling layer in the gas environment.

Catalytic hydroconversion of HTL micro-algal bio-oil into biofuel over NiWS/Al2O3

The demand for energy worldwide and the environmental concerns are increasing over the years, and microalgae is a potential raw material for third-generation fuel. In this work, the Chlorella sorokiniana microalga was converted by hydrothermal liquefaction (HTL) into a bio-oil using a batch reactor at 300 °C, under 10 MPa, for 30 min. Then, the bio-oil was upgraded using a batch reactor at three temperatures (350 °C, 375 °C, and 400 °C) under 10 MPa (H2) over NiW/Al2O3 sulfided catalyst. The bio-oil and upgraded fractions were characterized by elemental analysis, GPC-RID/DAD, 13CNMR, Sim-Dis, and GC×GC–MS/FID to identify the bio-oil molecular composition and follow its evolution. The lipids in the initial biomass, composed mainly of C16 and C18 chains/triglycerides, were converted into C16 and C18 fatty acids during the HTL reaction, corresponding to 41 % of bio-oil. Then, during the upgrading stage, these carboxylic acids were converted into C15 to C18 n-alkanes through two routes: hydrogenation or decarboxylation/decarbonylation, which was favored by temperature increase. >60 % of upgraded bio-oil eluted on the diesel range, as observed by Sim-Dis. The higher heating value (HHV) increased from 36 MJ/kg in the HTL bio-oil to 47 MJ/kg in the oil upgraded at 400 °C, and the average molar mass decreased from 333 to 203 g/mol. Oxygen and nitrogen compounds such as phenols, phytosterols, pyrroles, indoles, carbazoles, and amides were identified and quantified. Some insights about sulfur compounds are also given. The degree of deoxygenation, denitrogenation and desulfurization was higher than 90 % after the upgrading stage at 400 °C. Nevertheless, heterocyclic nitrogen compounds remained in the upgraded biooil. Therefore, catalytic hydrotreatment is confirmed as a relevant technology for upgrading HTL micro-algal bio-oil. However, catalyst performances can be improved to reduce less reactive nitrogen components.

The structure and properties of mechanochemically modified acrylonitrile butadiene rubber (NBR)/poly (vinyl chloride) (PVC) scraps and fresh NBR composites

Vulcanized acrylonitrile-butadiene rubber (NBR)/poly (vinyl chloride) (PVC) blends are mainly served as insulation rubber-plastic materials. However, methods to reuse the waste NBR/PVC composites lack research. Here, we found that the mechanochemically modified waste NBR/PVC composites powders (WNPP) could be an alternative to fresh NBR. According to the results, the optimal replacement amount of WNPP for NBR was 20%, and the highest feasible proportion was 40%. WNPP treated by solid-state shear milling technology (S3M) would have a high degree of desulfurization, and the cross-linked chains within WNPP would be transformed into free chains. While co-vulcanizing, the sulfur agents and heat would induce the free chains of WNPP to react with the polymer chains of the NBR substrate, thereby generating dangling chains to form a robust interfacial layer. It was beneficial for the improvement of the mechanical properties of reclaimed products. And the strain of the excellent recycled sample (20C) reached 707%. Moreover, the modified WNPP in the co-vulcanized rubber represented heterogeneity because of the internal residual crosslinked network and the not-melting PVC plastic phase. Although the heterogeneity of WNPP damaged the continuity of the NBR matrix, it also brought a better hysteresis loss capability to the composite. In conclusion, this work expanded the mechanochemical application scope in recycling NBR/PVC wastes.

Oxidative desulfurization with hydrogen peroxide of catalytic cracking and coking gasolines produced from a mixture of Azeri oils

To extract sulfur compounds from oils, hydrogenation processes with a high consumption of hydrogen using expensive platinum catalysts, etc are implemented. In this regard, we have studied the process of oxidative desulfurization of catalytic cracking gasoline (CCG) and coking gasoline (CG) with hydrogen peroxide, as well as their narrow fractions, using cobalt-, molybdenum-containing and iron oxide catalysts with further extraction of sulfur-oxidized compounds with ionic liquids (morpholinium formate). The initial sulfur content in CCG and CG is 397 and 1558 ppm, respectively. After oxidation and extraction with an ionic liquid of oxidized CCG and CG, the sulfur content was 100.4 and 336.4 ppm, respectively. The degree of desulfurization in this case for CCG and CG is equal to 74.7 and 78.4 %, correspondingly. The degree of desulfurization of gasoline fractions ranged from 70 to 85 % with virtually no change in the ON (octane number) of gasoline.

Photochemical reaction kinetics research over substituted metal phthalocyanine/La0.8Ce0.2NiO3 catalysts during the desulfurization process of dibenzothiophenes

Among many photocatalysts, metal phthalocyanine-sensitized semiconductor material has become a research hotspot as an efficient deep desulfurization catalyst. In this work, three series modified phthalocyanine, under nitro, amino and carboxyl as substituted groups, have been obtained firstly and named MTNPc, MTAPc, and MTcPc (M = Mn (II), Fe (II), Co (II), Ni (II), Cu (II)). The corresponding metal phthalocyanine/La0.8Ce0.2NiO3 composite catalysts have been successfully synthesized by impregnation method. Through the study on the photocatalytic oxidation desulfurization of DBTs under simulated sunlight, it was found the effect of central metal ions on the catalyst activity is related to their valence electron configuration, while the substituted groups are attributed to their own properties. For the further research, the kinetic study has been introduced to restore the actual reaction process, finding it conformed to the quasi-first reactions and the order of desulfurization degree of the catalysts with the same central metal ions and different peripheral substituted groups is MTcPc/La0.8Ce0.2NiO3 > MTNPc/La0.8Ce0.2NiO3 > MTAPc/La0.8Ce0.2NiO3. Besides, the CoTcPc/La0.8Ce0.2NiO3 with the best desulfurization performance shows t1/2 = 74 min and the reused experiment has been done to study their actual use value.

Effect of High Content of Waste Tire Rubber and Sulfur on the Aging Behavior of Bitumen

High content rubber modified bitumen (HCRMB) prepared from the high content of waste tire rubber and bitumen has good performance while allowing greater use of the waste tires. However, HCRMB is subject to aging during use, which can affect its performance. The purpose of this paper was to investigate the effect of high content of waste tire rubber and sulfur on the aging behavior of bitumen. The properties of all bitumen were tested using rolling thin film oven aging (RTFOT) test, pressure aging vessel (PAV) test, frequency sweep tests, temperature sweep (TS) test, multiple stress creep recovery (MSCR) test, and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) test. Test results show that the addition of sulfur to HCRMB leads to an improvement in the elasticity of HCRMB. The elasticity of HCRMB with different amounts of sulfur increases with aging. In addition, the increase in the amount of sulfur can improve the RTFOT aging resistance and the PAV aging resistance of HCRMB. Sulfur cannot reduce the degree of oxidation of HCRMB after aging, but can inhibit the degree of desulfurization of HCRMB. Furthermore, the aging process of HCRMB with different amounts of sulfur is dominated by the degradation of polybutadiene.

One-step oxidative-adsorptive desulfurization of DBT on simulated solar light-driven nano photocatalyst of MoS2-C3N4-BiOBr @MCM-41

Using a catalyst-adsorbent for simultaneous oxidation and adsorption of sulphuric compounds in liquid fuels is an effective and economical way. Thus in this paper, the core–shell MoS2-C3N4-BiOBr@MCM-41 photocatalyst-adsorbents with different percentages of MoS2 (1, 3, and 5 wt%) were prepared and used in a one-step photo oxidative-adsorptive desulfurization under simulated solar light. Thesamples were characterized by XRD, FESEM, FTIR, EDX, BET-BJH, TEM, UV–Vis DRS, and PL analyses. Theresults indicated that the final C/C0decreased from 0.42 to 0.016 with increasing the MoS2percentage (98.4% conversion). Despite the lowest surface area (845 m2/g) and the broad bandgap energy (2.8 eV), the sample with 5 wt% of MoS2illustrated the most degree of desulfurization due to strong interaction between components, the highest coverage of MCM-41 with active phases, high population of structural defects, high capability of light absorption and low recombination rate of charge carriers. GC-MS analysis indicated no DBT, DBTO or DBTO2 in the treated fuel. However, the presence of DBTO2 on the surface of the photocatalyst was confirmed that reveals the successful one-step oxidative-adsorptive desulfurization on the MoS2-C3N4-BiOBr@MCM-41. The adsorption mechanism was consistent with the pseudo-second-order kinetics, indicating that the rate-limiting step was chemical adsorption. Moreover, selectivity evaluations showed that while MoS2-C3N4-BiOBr@MCM-41 photocatalyst had high activity in the desulfurization of DBT, its affinity for adsorption and photocatalytic oxidation of non-sulfur aromatic compounds such as benzene, xylene and toluene was very low.

Formation of pyrite in the process of fine coal desulfurization by microwave enhanced magnetic separation

ABSTRACT Coal desulfurization, one of the important research objectives of clean coal technology, has been attracting great importance globally, especially by coal producing and coal consuming countries. Developing clean coal preparation technology before combustion is of great significance to decrease the pollutant emission to the environment and promote efficient and clean utilization of coal energy resource. This study investigated the effect of feed size of – 0.5 mm (finer than 0.5 mm, similarly hereinafter) size pulverized coal, microwave treatment time, and the transformation law of pyrite was characterized by X-ray diffraction (XRD) and X-ray phosphorescence technology (XPS). The results show that with increasing microwave treatment time, the pyrite in the pulverized coal is first transformed into pyrrhotite and then troilite. The order of magnetism in these coal products is as follows: Pyrrhotite > Troilite > pyrite. In addition, the specific magnetization of fine coal first increases and then decreases. With decreasing particle size, the specific magnetic susceptibility X 0 of fine coal decreases gradually; however, the desulfurization degree, Srej, increases gradually. The desulfurization degree of – 0.074 mm fine coal is twice that of the coal particles with the size in the range 0.3–0.5 mm. Magnetic separation of pulverized coal effectively enhanced the desulfurization effect.

Promotion effect of sulfur impurity in alumina support on propane dehydrogenation

Alumina materials are widely applied either as a catalyst or support in various industrial catalytic processes. Impurities in alumina that are unfriendly to catalytic performance are inevitably present during the production processes. Facing this problem, we here report that the use of sulfur-containing alumina as the support can generate active alumina-supported platinum catalyst, which exhibits superior propylene selectivity and anti-coking ability during propane dehydrogenation. It demonstrated that the sulfur impurity in alumina is not entirely detrimental. During the reduction process, the formation of gas-phase sulfur species increased the electrons and poisoned unsaturated sites of platinum particles. The sulfur impurity in alumina can be removed through a hydrogen reduction process, and the degree of desulfurization is correlated with the operating temperature. This study demonstrated that the rational use of impurity will contribute to the design of a catalyst with high reactivity for potential applications.