Utilizing environmentally-friendly bacterial cellulose as a scaffold, a highly porous, layered OA-BC catalyst was synthesized through an enhanced sol-gel process. This catalyst demonstrated exceptional performance in the oxidation of toluene, outperforming conventional alternatives that utilize chemical porogens. The OA-BC catalyst efficiently degrades toluene at 220℃ with high stability and hydrophobicity, indicating resistance to deactivation. Its superior activity is due to increased oxygen vacancies, enhanced metal oxide cooperation, and a layered porous structure, which together enhance active oxygen species and oxygen diffusion. Calcination of the OA-BC catalyst results in molecular cleavage and formation of small aggregates, increasing hydroxyl groups that stabilize Cu and Ce centers, enhancing toluene-oxygen reactions. In-situ infrared and X-ray photoelectron spectroscopy confirm stable monodentate Cu+ ligands, contributing to its high catalytic activity. This study introduces a novel approach by employing bacterial cellulose as a template for synthesizing a porous stratified OA-BC catalyst, demonstrating superior performance in toluene oxidation. The efficacy of catalyst results from a tripartite synergy involving the stratified porous architecture, the stabilizing effect of Cu+-coordinating ligands and hydroxyl groups, and the interplay of hydroxyl electron donors and acceptors, shedding light on environmentally benign catalyst development.

采用溶胶凝胶法制备了双主金属、双助剂的CuxMn1-xCe0.75Zr0.25Oy催化剂,在固定床反应器中评价了催化剂降解甲苯的性能,并采用XRD、H2-TPR、O2-TPD和Raman对催化剂进行表征.试验结果表明:催化剂中Cu含量的增加有助于增强Cu-Ce金属之间的相互作用,增加催化剂中的氧空位浓度和晶格氧含量,提高催化剂低温还原性,从而促进催化活性的提高.Cu1CeZr催化剂降解甲苯活性最好,其完全降解甲苯的温度(T100)为220℃,比Mn1CeZr催化剂低60℃.

采用简单的溶胶–凝胶法在不同的温度下制备Cu0.5Ce0.375Zr0.125Ox复合氧化物催化剂,通过XRD、H2-TPR、O2-TPD和Raman技术表征催化剂的结构,在固定床反应器中对其降解甲苯性能进行研究.结果表明:溶胶–凝胶的温度对催化剂的结构和活性具有一定影响,适宜的溶胶–凝胶温度有利于增强金属离子的流动性,促进CuO和CeO2的相互作用,使Cu2+更容易进入到CeO2晶格中形成Cu-Ce固溶体,形成缺陷结构,产生更多的氧空位.当催化剂制备的溶胶–凝胶温度为70℃时,催化剂降解甲苯的活性最好,其完全降解甲苯的温度为250℃.这归因于该催化剂具有高达0.95的氧空位浓度和对活性起主要作用的活性物种较高的耗氢量.

Highly active CuO-CeO2-ZrO2 catalysts were prepared by sol-gel method, using environmentally friendly bacterial cellulose (BC) as structure directing regent. The catalyst designed with commercial BC (Corn-BC) exhibited catalytic performances in toluene (T-100 = 220 degrees C) and ethyl acetate oxidation (T-100 = 170 degrees C) superior to the catalysts prepared by traditional methods. Furthermore, excellent stability was obtained and no deactivation was observed during the 100 h on stream in toluene and ethyl acetate oxidation at T-100. The excellent activity and stability of Corn-BC can be explained by the hierarchically porous structure, abundant oxygen vacancies, and good reducibility.

选用细菌纤维素(BC)、草酸(OA)和乙二醇(EG)为造孔剂,采用溶胶凝胶法制备了Cu-Mn双主金属Ce-Zr双助剂复合氧化物催化剂,在固定床反应器中评价了其催化降解甲苯的性能,用低温N2物理吸脱附、XRD、H2-TPR和Raman方法对催化剂进行表征.结果表明:催化剂的组成相同时,以生物基细菌纤维素为造孔剂制备得到的Cu0.25Mn0.25Ce0.375Zr0.125Ox-BC催化剂降解甲苯的活性明显高于化学造孔剂草酸和乙二醇制备的催化剂,其完全降解甲苯的温度为240℃,比化学造孔剂制备的催化剂低10～30℃;高的氧空位浓度(0.726)和好的低温还原性是Cu0.25 Mn0.25Ce0.375Zr0.125Ox-BC催化剂具有降解甲苯高活性的主要原因.

以TiO2为载体,采用等体积浸渍法制备了负载型CuxMn1-xCe0.75Zr0.25/TiO2(x=1.0、0.75、0.5、0.25、0)负载型催化剂,采用XRD、H2-TPR、O2-TPD和XPS等方法对催化剂进行了表征,并通过低温等离子体协同催化剂对大流量的甲苯模拟废气进行了催化降解反应研究.结果表明,Cu和Mn单主金属催化剂的活性优于Cu-Mn双主金属催化剂,其原因是双金属催化剂中Mn的添加减弱了Cu与助剂Ce之间的相互作用,使得催化剂的晶格氧减少,低温还原性能降低.在反应初期,甲苯降解主要依赖于催化剂的活性,具有较好的低温还原性以及丰富的氧空穴和晶格氧含量的CuCe0.75 Zr0.25/TiO2的活性最好;Mn具有较强的O3分解能力,当等离子体比能密度(SED)增加到一定值后,等离子体与催化剂的协同作用增强,从而使得MnCe0.75 Zr0.25/TiO2催化剂活性高于CuCe0.75 Zr0.25/TiO2,强化了甲苯的脱除.

The self-sustained combustion of toluene on the Cu-Ce-Zr based catalysts with different activity has been carried out in a micro-tube with inner diameter of 4 mm. It was shown that the lean-combustion limits over CuCe0.75Zr0.25Ox-BC catalyst with the higher activity were less than that on CuCe0.75Zr0.25/TiO2 catalyst at the same flow rate, and the minimum of equivalence ratio (?) was 0.024 under the flow rate of 200 ml/min. The residence time of the mixed gas on the catalyst surface declined with the increasing of flow rate, making the highest surface wall-temperature range shift to the back of catalyst bed. Toluene could maintain self-sustained combustion even when the heat loss was as high as 91.9%. Combined with the theoretical model, the heat transport of toluene self-sustained combustion in micro-tube was calculated. The self-sustained combustion in a fixed-bed reactor was realized with reducing the upper limit of temperature runaway??s impacts for the reactor and catalysts.

A series of CuCe0.75Zr0.25Ox catalysts (CCZ) were synthesized based on the environmental-friendly bacterial cellulose (BC) by using the sol-gel method. The corresponding synthesis mechanism, physicochemical properties of the catalysts and catalytic performances for toluene oxidation were comprehensively studied. In the presence of BC without sugar, the CCZ-A synthesized by ethanol-gel exhibits better catalytic activity than the CCZ-W synthesized by water-gel, which may be due to the different roles of BC in different solvents. However, it is worth noting that the graft copolymerization between BC and active metal (Ce4+, Cu2+) is the same process in both water-gel and ethanol-gel. The activity of CCZ-SW synthesized by water-gel using BC with sugar is obviously higher than that of CCZ-W and CCZ-A. The temperature of complete degradation of toluene over CCZ-SW is 205 degrees C, which is 35 degrees C lower than that of CCZ-W. The results from BET, Raman and H-2-TPR indicate that the larger the specific surface area, the more oxygen vacancies and better low-temperature reducibility, that are mainly responsible for the excellent activity of CCZ-SW. The existence of sugar in BC could hinder the agglomeration of active metal particles during the calcination process. Combined with the results of insitu DRIFT, the adsorbed toluene on the catalyst surface is oxidized into alkoxide, aldehydic and carboxylic acid species as intermediates before the complete oxidation into CO2 and H2O.((1))

The catalytic self-sustained combustion of toluene over CuxMn1-xCe0.75Zr0.25/TiO2 catalysts (x = 1, 0.5, 0) was studied in a microscale combustor. The catalytic activity is determined not only by the temperature with toluene conversion of 90% (T-co), but also by the corresponding lean-combustion limits. It was found that the self-sustained combustion was achieved successfully over the catalysts, with the toluene concentrations of 0.35 con.%, 0.50 con.% and 1.00 con.%. According to T-co,T- the activity decreased in the order of CuCe0.75Zr0.25/TiO2 (234 degrees C) > Cu0.5Mn0.5Ce0.75Zr0.25/TiO2 (238 degrees C) > MnCe0.75Zr0.25/TiO2 (284 degrees C). The excellent activity of CuCe0.75Zr0.25/TiO2 catalyst could be ascribed to the high content of active lattice oxygen, good low-temperature reducibility and homogeneous dispersion, combined with the results of H-2-TPR, O-2-TPD and XPS. Furthermore, the results of in-situ DRIFT and temperature-programmed oxidation (TPO) of toluene in N-2 atmosphere suggested that toluene was adsorbed on the catalyst surface by removing alpha-H from methyl and combining with active oxygen specie to form benzyl group, which was finally oxidized into CO2 and H2O with lattice oxygen.

Mesoporous CuCe0. 75 Zr0. 25 Ox composite was prepared by a simple sol-gel method with environmentally benign bacterial cellulose ( BC) as a pore former and characterized by TG/DTG, N2 adsorption-desorption, XRD, H2-TPR, O2-TPD and Raman; its catalytic activity in the degradation of toluene at low temperature was investigated in a fixed-reactor. The results indicated that BC with ultra fine three-dimensional networks and excellent compatibility is beneficial to the formation of gel with nitrate solution, to prepare the mesoporous catalyst. The catalyst performance of CuCe0. 75 Zr0. 25 Ox composite is significantly affected by the gel-form and gelling temperature during the preparation process. Over the ACCZ-70 catalyst prepared by alcohol gelling at 70℃, the temperature for a complete degradation of toluene ( T100 ) reaches 205℃, much lower than those reported in open literature; the excellent activity of ACCZ-70 is ascribed to its high reducibility at low temperature and high concentration of oxygen vacancies (0. 81). In addition, adsorption phenomenon was observed in the range of 120-140 ℃ during the toluene degradation over WCCZ catalysts prepared by water gelling.