Catalytic feasibility of Ce-doped LaCoO3 systems for chlorobenzene oxidation: An analysis of synthesis method

A family of Ce-doped LaCoO₃ perovskites are presented as possible catalysts for Cl–VOCs elimination. These materials with different contents of Ce were obtained through the citrate and the reactive grinding methods. The insertion of Ce in the original perovskite structure favours the presence of Co²⁺/Co³⁺ and Ce³⁺/Ce⁴⁺ redox pairs and a higher content of oxygen vacancies that enhances the catalytic performance in chlorobenzene combustion based on differential kinetics studies. The family obtained by the grinding method presents a performance as high as that synthesized by citrate method. Thus, the reactive grinding is a feasible green chemistry alternative to obtain a catalyst with the same performance as that obtained from traditional methods. Finally, the stability of samples was evaluated under total combustion reaction conditions showing an excellent activity during 45 h time on stream.     

固体酸催化剂作用下氯苯硝化的区域选择性研究

制备了SO^2-4/ZrO2催化剂并研究了该催化剂作用下硝酸硝化氯苯的区域选择性，反应具有强对位选择性硝化能力，催化剂经500℃焙烧后，在反应温度为30℃和反应30min时，氯苯一硝化产物中邻／对硝基氯苯异构体的质量比达0．23，产物得率可达55．5％，催化剂重复使用4次，其催化活性减少不大。     

Removal of the persistent pollutant chlorobenzene by adsorption onto activated montmorillonite

The potential of activated bentonite was assessed for adsorption of chlorobenzene from aqueous solution. The bentonite used was treated by chemical and thermal activation over 100–500 °C. The thermal activation increased the adsorption capacity more strongly than chemical activation which consists to acid and hydrogen peroxide treatment. The removal is dominated by adsorption at low initial concentrations and low temperatures and favourable in acidic media. The dependence of the adsorption on pH appears to be related to the solubility of chlorobenzene. Thermodynamic parameters such as ΔH°, ΔS°, ΔG° and Ea have been calculated. The adsorption process is spontaneous and exothermic in nature. The Freundlich isotherm described the adsorption data over the concentration range (20–270 °C).     

Catalytic transfer dechlorination of chlorobenzene over Pd/SBA-1 mesoporous molecular sieves

New dehalogenation catalysts Pd/SBA-1 mesoporous molecular sieves are synthesized and characterized by N₂ adsorption/desorption, XRD, XPS, FT-IR, DR-UV–vis and AAS. In liquid-phase catalytic transfer hydrogenation of chlorobenzene reaction, low Pd content catalyst Pd/SBA-1 is found to be an efficient catalyst in water/ethanol (2/3) solution of NaOH. The catalyst can easily be recovered and efficiently reused at least three times.     

顶空-气相色谱法同时测定生活饮用水及水源水中氯苯类化合物

采用顶空-气相色谱法同时测定生活饮用水及水源水中1,2-二氯苯、1,4-二氯苯、1,2,3-三氯苯、1,2,4-三氯苯、1,3,5-三氯苯、六氯苯6种氯苯类化合物。测定结果的相对标准偏差为1.6%~2.8%。回收率为95.9%~100.4%。通过实样分析验证了方法的适用性。     

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.     

氯苯在HZSM-5分子筛上选择性硝化的研究

研究了以HZSM-5分子筛为催化剂,氯苯-硝基化反应中各反应参数即反应物配比、反应时间、反应温度、催化剂用量以及HZSM-5分子筛硅铝比对p/o的影响。结果使用SiO_2/Al_2O_3为40的HZSM-5分子筛作催化剂可使p/o达到4.60,氯苯转化率21.0％。     

对氯苯磺酰氯的合成进展及改进方向

本文介绍了精细化工中间体对氯苯磺酰氯的用途，及其重要的后续产品聚砜的优良特性和巨大的市场潜力，列举了国内外对氯苯磺酰氯的几种工业化生产工艺及其所造成的环境问题，综述了过量氯磺酸法制取对氯苯磺酰氯的研究进展，最后在不改变国内工业原料路线的前提下，根据氯磺化的反应机理．依据清洁生产的思想，从改变工艺操作、选用惰性溶剂及运用固相分离介质等几个方面提出改进传统过量氯磺酸法生产工艺的一些思路。     

Influence of Pd Precursor and Method of Preparation on Hydrodechlorination Activity of Alumina Supported Palladium Catalysts

A series of alumina supported Pd catalysts were prepared by the novel deposition-precipitation method adopting the chloride precursor (DP-Cl) of Pd and varying the metal content from 0.25 to 1.0 wt%. The catalytic properties of prepared catalysts were studied by various characterization techniques such as N₂ adsorption, CO chemisorption, TPR, XRD, XPS, and TEM techniques. The activity and stability of the catalysts were evaluated for the gas phase hydrodechlorination (HDC) of chlorobenzene operating at atmospheric pressure. At 1 wt% of Pd the catalyst showed higher chlorobenzene conversion with good stability when tested for a period of 25 h, whereas the other catalysts exhibited a loss in activity with time. In order to elucidate the exceptional activity and stability of this catalyst, a few more catalysts with 1 wt% Pd were prepared by impregnation technique and also using a non-chloride precursor, palladium nitrate. The 1 wt% DP-Cl catalyst again was found to be the best among the others. The activity and stability of the DP-Cl catalyst was also found to be superior to two low-dispersed catalysts, each with 10 wt% Pd, prepared by conventional impregnation method using the chloride and nitrate as the precursors. The characterization results reveal that the high activity and stability of the DP-Cl catalyst is related to the formation of electron deficient Pd species and its stabilization in the octahedral vacancies of alumina.     

甲基丙烯酸水溶液萃取分离研究

以氧化叔丁醇或异丁烯合成甲基丙烯酸所产生的水溶液需要进行萃取分离。本文通过实验测定了各种溶剂的萃取率,研究了不同萃取温度的影响,考察了分别以水溶液和萃取剂为连续相的萃取效率,分析了萃取絮状物的产生原因,确定了萃取溶剂、温度和连续相等萃取工艺条件。