H_2S Removal with Cupric Chloride for Producing Sulfur

1 INTRODUCTION The removal of H2S from biogas, natural, or in- dustrial gases is a great concern in environmental technology, because this gas is extremely hazardous to human health and corrosive, besides its strong un- pleasant smell. It is produced during the anaerobic treatment of wastewater and during effluent treatment in some industries such as paper and sour products or in petrochemical and natural gas refineries[1]. The Claus process has been most commonly em- ployed to remove H2…     

Enhanced stability of nitrogen-doped carbon-supported palladium catalyst for oxidative carbonylation of phenol

Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst (Pd/NCF) was prepared by supporting Pd ultrafine metal nanoparticles (NPs) on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen source.The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepar...     

CHEMOSELECTIVE PREPARATION OF CHLOROSULFONYL-CONTAINING AZO-DYES WITH THIONYL CHLORIDE-N,N-DIMETHYLFORMAMIDE

INTRODUCTION Azo-dyes containing chlorosulfonyl group are important intermediates of dyes for use in instant photography[1] and sulfonamido-containing disperse dyes[2].Chlorination of azo-dyes containing sulfonic acid group to the corresponding sulfonyl chlorides is an important method for the synthesis of this kind of compounds.Many approaches to performing the aforementioned conversion have been developed.One approach involves the use of chlorosulfonic acid[3],but the reagent is difficult to handle and can not be recycled.Another approach involves using phosphorous pentachloride as chlorination reagent[4], however,it is too expensive to be scaled up.The third one uses phosphoryl chloride-N,N-dimethylacetamide(POCl3-DMA)[2],in which acetonitrile and sulfolane are used as reaction medium[2],but a large amount of DMA is used and sulfolane can not be recycled easily due to its high boiling point.     

有机溶剂中树脂催化丙酮氰醇分解反应的动力学模型

Decomposition of acetone cyanohydrin is the first-step reaction for preparing (S)-α-cyano-3-phenoxybenzyl alcohol (CPBA) by the one-pot method in organic media. Considering the compatibility of bio-catalysts with chemical catalysts and the successive operation in the bioreactor, anion exchange resin (D301) was used as catalyst for this reaction. External diffusion limitation was excluded by raising rotational speed to higher than 190r·min-1 in both solvents. Internal diffusion limitation was verified to be insignificant in this reaction system. The effect of acetone cyanohydrin concentration on the reaction was also investigated. An intrinsic kinetic model was proposed when the mass transfer limitation was excluded, and the average deviation of the model is 10.5%.     

Catalytic ozonation of volatile organic compounds (ethyl acetate) at normal temperature

Catalytic treatments of VOCs at normal temperature can greatly reduce the cost and temperature of processing, and improve the safety factor in line with the requirements of green chemistry. Activated carbon fiber(ACF) was pretreated with 10% H_2SO_4 by single factor optimization to increase specific surface area and pore volume obviously. The catalytic ozonation performance of ACF loaded with Au, Ag, Pt and Pd noble metals on ethyl acetate was investigated and Pd/ACF was selected as the optimal catalyst which had certain stability. Pd is uniformly distributed on the surface of ACF, and Palladium mainly exists in the form of Pd~0 with a amount of Pd~(+2). The specific surface area of the catalysts gradually decreases as the loading increases. The activation energy of ethyl acetate calculated by Arrhenius equation is 113 kJ·mol~(-1). With 1% Pd loading and the concentration ratio of ozone to ethyl acetate is 3:1, catalytic ozonation performance is maximized and the conversion rate of ethyl acetate reached to 60% in 30–50 ℃ at 15,000–30,000 h~(-1).     

水溶性铑络合物催化1-十二碳烯氢甲酰化反应器构型的初步探索

Hydroformylation of 1-dodecene was studied in a biphasic system using water-soluble rhodium complex [RhCl(CO)(TPPTS)2] as catalyst in the presence of cetyl trimethyl ammonium bromide as surfactant to enhance the reaction rate. Efforts were devoted to improve the performance of hydroformylation by exploring reactor the reaction configuration which enhanced the mixing, dispersion and interphase mass transfer. Experiments were carried out in a 0.5L autoclave at the total pressure of 1.1MPa and temperature from 363K to 373K. Several surface aeration configurations were tested, and higher hydroformylation rate with higher normal/branched aldehyde ratio produced were achieved. The experience suggest that improved reactor configuration by taking reaction engineering, measures is beneficial to better process economy in alkene hydroformylation.     

Benzene selective hydrogenation over supported Ni (nano-) particles catalysts: Catalytic and kinetics studies

This report aims to reduce the benzene in a mixture of benzene and toluene as a model reaction using catalytic hydrogenation. In this research, we developed a series of catalysts with different supports such as Ni/HMS, Ni/HZSM-5, Ni/HZSM5-HMS, Ni/Al_2O_3 and Ni/SiO_2. Kinetic of this reaction was investigated under various hydrogen and benzene pressures. For more study, two kinetic models have also been selected and tested to describe the kinetics for this reaction. Both used models, the power law and Langmuir–Hinshelwood, provided a good fit toward the experimental data and allowed to determine the kinetic parameters. Among these catalysts, Ni/Al_2O_3 showed the maximum benzene conversion(99.19%) at 130 °C for benzene hydrogenation. The lowest toluene conversion was observed for Ni/SiO_2. Furthermore, this catalyst presented high selectivity to benzene(75.26%)at 130 °C. The catalytic performance(activity, selectivity and stability) and kinetics evaluations were shown that the Ni/SiO_2 is an effective catalyst to hydrogenate benzene. It seems that the surface properties particularly pore size are effective parameter compared to other factors such as acidity and metal dispersion in this process.     

Research progress in ionic liquids catalyzed isobutane/butene alkylation

The complicated reaction mechanism and the character of competitive reactions lead to a stringent requirement for the catalyst of C4 alkylation process. Due to their unique properties, ionic liquids (ILs) are thought to be new potential acid catalysts for C4 alkylation. An analysis of the regular and modified chloroaluminate ILs, novel Br?nsted ILs and composite ILs used in isobutane/butene alkylation shows that the use of either ILs or ILs coupled with mineral acid as homogeneous catalysts can help to greatly adjust the acid strength. By modifying the struc-tural parameters of the cations and anions of the ILs, the solubility of the reactants could also be adjusted, which in turn displays a positive effect on improving the activity of ILs. Immobilization of ILs is an effective way to mod-ulate the surface adsorption/desorption properties and acid strength distribution of the solid acid catalysts. Such a process has a tremendous potential to reduce the deactivation of catalyst and enhance the activity of the solid acid catalyst. The development of novel acid catalysts for C4 alkylation is a comprehensive consideration of acid strength and its distribution, interfacial properties and transport characteristics.     

对苯二甲酸-丁二醇催化单酯化反应动力学(英文)

The chemical kinetics of the monoesterification between terephthalic acid (TPA) and 1,4-butanediol (BDO) catalyzed by a metallo-organic compound was studied using the initial rate method. The experiments were carried out in the temperature range of 463-483 K, and butylhydroxyoxo-stannane (BuSnOOH) and tetrabutyl titanate [Ti(OBu)4] were used as catalyst respectively. The initial rates of the reaction catalyzed by BuSnOOH or Ti(OBu)4 were measured at a series of initial concentrations of BDO (or TPA) with the concentration of TPA (or BDO) kept constant. The reaction orders of reagents were determined by the initial rate method. The results indicate that the reaction order for TPA is related with the species of catalyst and it is 2 and 0.7 for BuSnOOH and Ti(OBu)4 respectively. However, the order for BDO is the same 0.9 for the two catalysts. Furthermore, the effects of temperature and catalyst concentration are investigated, and the activation energies and the reaction rate constants for the two catalysts were deter-mined.     

一种新γ相氧化铝负载的铁铝双金属催化剂用于反向水煤气转化反应(英文)

In reverse water gas shift (RWGS) reaction CO₂ is converted to CO which in turn can be used to produce beneficial chemicals such as methanol. In the present study, Mo/Al₂O₃, Fe/Al₂O₃ and Fe-Mo/Al₂O₃ catalysts were synthesised using impregnation method. The structures of catalysts were studied using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, inductively coupled plasma atomic emission spectrometer (ICP-AES), temperature programmed reduction (H₂-TPR), CO chemisorption, energy dispersive X-ray (EDX) and scanning electron microscopy (SEM) techniques. Kinetic properties of all catalysts were investigated in a batch reactor for RWGS reaction. The results indicated that Mo existence in structure of Fe-Mo/Al₂O₃ catalyst enhances its activity as compared to Fe/Al₂O₃. This enhancement is probably due to better Fe dispersion and smaller particle size of Fe species. Stability test of Fe-Mo/Al₂O₃ catalyst was carried out in a fixed bed reactor and a high CO yield for 60 h of time on stream was demonstrated. Fe₂(MoO₄)₃ phase was found in the structures of fresh and used catalysts. TPR results also indicate that Fe₂(MoO₄)₃ phase has low reducibility, therefore the Fe₂(MoO₄)₃ phase signifificantly inhibits the reduction of the remaining Fe oxides in the catalyst, resulted in high stability of Fe-Mo/Al₂O₃ catalyst. Overall, this study introduces Fe-Mo/Al₂O₃ as a novel catalyst with high CO yield, almost no by-products and fairly stable for RWGS reaction.     

New catalysts for the environmentally friendly processing of chlorinated organics

New, high-efficiency Pd and Ni catalysts for the environmentally friendly processing of chlorinated organic waste have been prepared by laser electrodispersion (LED). The nanostructured catalysts contain ensembles of Pd and Ni nanoparticles 2 and 2.5 nm in size, respectively, and show an exceptionally high activity (above 10⁵ (mol products)/(mol metal h)) in the gas- and liquid-phase hydrodechlorination of chlorobenzenes at t < 200°C. The activity of the Pd-based supported catalysts prepared by conventional methods is lower by approximately three orders of magnitude. Another significant advantage of the new catalysts is that they are highly resistant to poisoning under the conditions of the catalytic reaction. The structure and catalytic properties of the catalysts remain unchanged as the process is run for several days. The improved performance of the nanostructured catalysts is due to charge redistribution between clusters or between a cluster and the support. This effect is most pronounced for ∼2-nm nanoclusters at incomplete (<50%) surface coverages of the support. Making use of this effect allows the amount of metal on the support to be reduced by three orders of magnitude. This is particularly important for catalysts based on noble and rare metals. The results presented here open up new opportunities for the development of an efficient and safe technology for the processing of organochloride waste by catalytic hydrodechlorination.     

四氯化碳催化加氢研究进展

从四氯化碳选择性加氢脱氯催化剂的活性组分、反应机理和催化剂失活及预处理等方面详细介绍了四氯化碳选择性加氢脱氯反应及催化剂的最新研究进展,简述了反应温度、压力和n(H2)/n(CCl4)比对四氯化碳催化加氢产品分布的影响,并指出了四氯化碳选择性加氢脱氯反应的发展方向。     

Hydrodechlorination of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) over supported ruthenium and other noble metal catalysts

The hydrodechlorination of CCl₂F–CClF₂ (CFC-113) was studied using silica- and activated carbon-supported Ru, Rh, Pd, and Pt catalysts. The activity of the catalysts changed with time-on-stream. Ru was most stable among the four noble metals and gave a simple product distribution yielding CClF=CF₂ (CFC-1113) and CHClF–CClF₂ (HCFC-123a) as main products. Over silica-supported Ru, CFC-1113 yield decreased gradually with time-on-stream but HCFC-123a yield did not change throughout the reaction, suggesting that these products were formed on different sites of Ru. XRD studies and temperature-programmed reduction of the spent catalyst revealed that the deactivation was caused by halogen-containing carbonaceous species accumulated on the Ru surface during the reaction. The carbonaceous species seemed to be formed on the active site for CFC-1113 formation. Because CFC-1113 selectivity was higher over the catalyst having higher Ru dispersion, it was assumed that the hydrodechlorination of CFC-113 is structure-sensitive and CFC-1113 formation is promoted by Ru having highly unsaturated coordination sphere.     

CFC-115加氢脱氯制HFC-125 Pd/C催化剂制备研究

以商品化活性炭为载体、贵金属Pd为活性组分,采用浸渍法制备了一系列Pd/C催化剂.在常压固定床微型反应器中,以CFC-115加氢脱氯生产臭氧消耗物质(ODS)替代品HFC-125为目标反应,评价了催化剂的性能.详细考察了载体预处理硝酸浓度、载体粒径、Pd源前驱体及溶剂等制备条件对其催化性能的影响.在研究的范围内,采用粉末活性炭为载体,Pd(NO_3)_2为Pd源,甲醇为溶剂制备的催化剂具有最好的催化性能.     

Hydrodechlorination of 3-chloropyridine and chlorobenzene in methanol solution over alkali-modified zirconia-supported palladium catalysts

The liquid-phase hydrodechlorination of 3-chloropyridine and chlorobenzene has been studied over alkali-modified zirconia-supported palladium catalysts. The modification of the ZrO₂ with alkali metal carbonates improves the catalytic activity of the final palladium catalyst. Therefore, the larger the ionic radii (Li⁺ < Na⁺ < K⁺), the greater the catalytic activity (TOF) of the palladium catalyst. For 3-chloropyridine, hydrodechlorination proceeds without catalyst deactivation. This is explained as the result of the interaction of reaction products (pyridine and HCl) forming pyridinium chloride, thus avoiding the detrimental effect of HCl on the palladium particles. Catalytic hydrodechlorination of chlorobenzene over Pd catalysts exhibits an initial catalytic activity (TOF) much lower than that of 3-chloropyridine and the Pd catalysts deactivate as the reaction proceeds. Finally, chlorobenzene hydrodehalogenation has also been carried out in the presence of an equimolecular amount of pyridine resulting in a decrease in the initial reaction rate on the one hand, but also in an increase in final conversion on the other.     

Low-temperature hydrodechlorination of chlorobenzenes on platinum-supported alumina catalysts

Hydrodechlorination of chlorobenzenes on platinum (Pt)-supported γ-alumina and alumina Lewis superacid (AmLSA) catalysts was carried out at room temperature and ambient pressure using a fixed bed flow reactor and a semi-batch reactor. Both the catalysts indicated good activity for the hydrodechlorination, but the former was superior to the latter. The hydrodechlorinations of reactants C₆H_6−xCl_x (x=1, 2, 3) proceeded step-wisely to benzene and then cyclohexane via C₆H_6−yCl_y (y=x−1). The reactions seem to be promoted by the contribution of spillover hydrogen formed on the Pt-supported catalysts. The catalysts deactivated with reaction time and the amount of chlorine that accumulated on the Pt-supported γ-alumina catalyst in the hydrodechlorination of 1,4-dichlorobenzene for 3 h was near to that estimated from the converted reactant molecules. When the deactivated catalysts were treated in a stream of hydrogen above 503 K, the original activity was completely restored, but the deactivation phenomenon with reaction time was observed again.     

纳米ZrO2负载Pd-Ni催化剂催化氯苯加氢脱氯性能研究

采用负载法制备了一系列纳米ZrO₂负载金属Ni、Pd催化剂，通过XRD、TEM和SEM等技术对催化剂进行了表征，并以氯苯的加氢脱氯为探针反应，考察了催化剂的加氢脱氯性能和反应温度、碱的用量、催化剂镍的含量等因素对催化活性的影响。结果发现，在80 ℃、NaOH和氯苯物质的量的比为1的反应条件下，Ni质量分数为10%和Pd为0.05%的Pd-Ni/ZrO₂催化剂效果最佳，反应9 h后氯苯的转化率可达到100%。     

Hydrodechlorination of alachlor in water using Pd, Ni and Cu catalysts supported on activated carbon

The hydrodechlorination of alachlor with hydrogen in aqueous phase was studied in a trickle bed reactor using different activated carbon-supported catalysts. The reactor was continuously fed with a 50 mg/L solution of alachlor in water and a H₂/N₂ gas stream. The variables studied were space-time (44.8–448.3 kg_cat h/mol), H₂:N₂ volumetric ratio in the gas phase (1:1–1:4), temperature (308–373 K) and pressure (0.24–0.6 MPa). The results of the hydrodechlorination experiments were evaluated in terms of alachlor conversion and ecotoxicity of the exit stream. High conversion values and important reductions of ecotoxicity were obtained working under mild conditions of temperature (323–348 K) and pressure (0.24 MPa). Palladium catalysts supported on activated carbon were found as the most active in the hydrodechlorination of alachlor, although copper and nickel catalysts led also to high conversions in the 80–93% range. The hydrodechlorination of alachlor was performed successfully with metal loads between 0.5 and 2.5 wt.% on the catalysts. A significant metal leaching was observed from the nickel and copper catalysts, which negatively affected the ecotoxicity of the final effluents. Oxidative treatment of the activated carbon supports with nitric acid previous to the impregnation with the metal precursor improved the anchorage of the active phase and reduced leaching dramatically. Likewise, the activity was not influenced by the oxidation of the supports and reductions of ecotoxicity by more than 90% were observed.     

CFC-113气固相加氢脱氯制备三氟氯乙烯的研究进展

综述了三氟三氯乙烷（CFC-113）气固相加氢脱氯制备三氟氯乙烯（CTFE）的国内外研究工作。该领域有传统锌粉法和气固相加氢脱氯两种具有工业化意义的工艺。相比锌粉法,加氢脱氯工艺具备清洁高效等优点,在应用于该工艺的众多催化剂体系中,贵金属Pd、Pt催化剂具有突出的活性,而助剂的选择则采用IB族元素为第一助剂,碱金属、镧系金属为第二、第三助剂为宜。目前该工艺尚有催化剂容易失活的问题亟待解决。     

糠醛脱羰制呋喃催化技术的研究进展

介绍糠醛脱羰法制备呋喃的2种生产方法:液相法和气相法。并详细评述了山西煤炭化学研究所的糠醛脱羰制呋喃的新工艺。同时,简介了贵金属和金属氧化物等2类催化剂的研究进展。最后,展望了我国大力发展糠醛脱羰制呋喃催化技术的应用前景,指出今后的研究方向是开发高效、对环境友好的催化剂和生产工艺。