钴铜双金属微波催化剂的制备及性能研究

以硝酸铜和硝酸钴为原料、尿素为沉淀剂,微波功率320 W,反应时间30 min,制备了钴铜双金属氢氧化物(CuCo-LDH)。通过表征结果得知,与其他制备方法相比,微波法制备的催化剂具有良好的结晶度、立体结构,并能提供更多的活性位点,具有较高的催化活性。在微波辅助下,CuCo-LDH中的Cu^(2+)、Cu^(+)、Co^(3+)、Co^(2+)与H_(2)O_(2)形成类芬顿反应耦合体系,甲基橙(MO)脱色率可达99.78%。本研究为双金属复合催化剂在水处理中的应用提供了有益参考。

钴铜层状双金属氢氧化物合成及其催化还原对硝基苯酚性能的研究

开发高效催化材料降解硝基有机污染物,对于推动绿色化学和化工的发展具有重要的意义。为此,研究了水浴法合成的钴铜层状双金属氢氧化物(CuCo-LDHs)将对硝基苯酚(4-NP)催化还原为对氨基苯酚(4-AP)的反应过程;通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、电感耦合等离子体光谱仪(ICP),对材料的晶体结构、表面形貌等进行了表征;同时系统性研究了催化剂用量,4-NP的初始浓度、反应温度及硼氢化钠(NaBH4)浓度对CuCo-LDHs催化还原性能的影响。研究结果表明:CuCo-LDHs在催化还原4-NP的反应中表现出较高的催化活性,且反应条件温和,产物无污染。在室温及反应时间为3 min条件下,10 mg CuCo-LDHs可将100 mL 0.10 mmol/L的4-NP有效还原,转化率可达到95%。最后对CuCo-LDHs催化还原4-NP生成4-AP的反应机理进行了分析讨论。

高活性类Fenton铜钴双金属催化剂的制备与性能研究

采用水热合成法制备具有高催化活性的纳米铜钴双金属氧化物(NCCO),并采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、傅里叶变换红外光谱仪(FTIR)、比表面与孔隙度分析仪(BET)等方法对其进行表征。通过改变制备条件,研究了NCCO在不同的前驱物用量配比、水热时间、水热温度以及有无超声预处理、有无丙醛添加等条件下的合成情况,并以硝基苯(NB)的降解效果为评价指标,确定NCCO的最佳制备条件。结果表明,在前驱物用量配比Cu∶Co为1∶1、水热时间为48 h、水热温度为200℃、超声预处理、添加丙醛的条件下,制得的NCCO具有最优的催化活性。此外,NCCO即使在连续使用4次后,45 min内对NB的降解率依然为100%,表明其具有优异的化学稳定性。

CO加氢合成低碳醇用CuCo/SiO_2催化剂的反应性能研究

采用共浸溃法制备了CuCo／SiO2双金属催化剂，以CO加氢合成低碳醇为模型反应考察了不同反应温度、压力和空速下催化剂的反应性能，并采用X射线（XRD）、热重分析（TG）和程序升温还原（TPR）技术对催化剂进行了表征。结果表明，（533～563）K，随反应温度升高，CO转化率从14．9％增加到40．4％，醇类的时空收率呈现先增大再减小的趋势，553K取得最优值；升高反应压力能显著提高醇类的选择性；（1200—4800）h^-1，随空速增加，CO加氢活性降低，醇类产物的选择性显著增加，使时空收率提高。XRD结果表明，反应前催化剂主要成分为CuO、Co3O4和CuCo尖晶石物相，反应后则为Cu^0和Co^2＋。TG和TPR结果表明，前驱体的适宜焙烧温度为623K，催化剂的原位还原温度为593K。

Supported Cobalt Molybdenum Bimetallic Nitrides for Ammonia Decomposition

Co and Mo bimetallic nitrides supported on Mg（Al）O, MgO and γ-Al2O3 were prepared in temperatureprogrammed reactions with NH3. The surface morphology, chemical composition and catalytic activity for NH3 decomposition on the supported Co and Mo bimetallic nitrides were studied by X-ray diffractometer （XRD）, NH3 temperature-programmed desorption and mass spectrometer （NH3-TPD-MS）, temperature-programmed desorption and mass spectrometer （TPD-MS）, H2 temperature-programmed surface reaction （H2-TPSR） and activity test. The phases of Co3Mo3N and MoN could be formed on Mg（Al）O, MgO and Al2O3 during the nitridation, and they might be more uniformly dispersed on Mg（Al）O and MgO than on γ-Al2O3. Transition metallic nitrides are generally considered as potential catalysts for hydrogen-involving reactions due to the entrance of hydrogen atoms into subsurface and the lattice of metallic nitrides. The diffusion of nitrogen in the bulk and the structure transformation of Co and Mo nitride compounds occur during NH3-TPD, but the supported Co and Mo bimetallic nitrides are not easily reduced at H2 atmosphere. Co3Mo3N/Mg（Al）O catalyst exhibits the highest activity, while Co3Mo3N/Al2O3 exhibits the lowest activity for NH3 decomposition. Furthermore, the catalytic activity of Co and Mo bimetallic nitrides is not only much higher than that of supported single metallic nitride, but also highly dependent upon the surface acidity and BET surface area of support.

Influence of supports for selective production of 2,5-dimethylfuran via bimetallic copper-cobalt catalyzed 5-hydroxymethylfurfural hydrogenolysis

The hydrogenolysis of carbon–oxygen bonds is an important model reaction in upgrading biomass‐derived furanic compounds to transportation fuels.One of these model reactions,namelyconversion of5‐hydroxymethylfurfural(HMF)to the gasoline additive2,5‐dimethylfuran(DMF),isespecially attractive.In this study,bimetallic Cu‐Co catalysts supported on CeO2,ZrO2,and Al2O3were used for the selective hydrogenolysis of HMF to DMF.The structures of the fresh and usedcatalysts were studied using X‐ray diffraction,the Brunauer‐Emmett‐Teller method,transmissionelectron microscopy,temperature‐programmed reduction by H2,temperature‐programmed desorptionof NH3,and CHNS analysis.The structures were correlated with the catalytic activities.TheCu‐Co/CeO2catalyst produced mainly2,5‐bis(hydroxymethyl)furan via reduction of C=O bonds onlarge Cu particles.The Cu‐Co/Al2O3catalyst gave the best selectivity for DMF,as a result of a combinationof highly dispersed Cu,mixed copper–cobalt oxides,and suitable weak acidic sites.Cu‐Co/ZrO2had low selectivity for DMF and produced a combination of variousover‐hydrogenolysis products,including2,5‐dimethyltetrahydrofuran and5,5‐oxybis(methylene)‐bis(2‐methylfuran),because of the presence of strong acidic sites.The reaction pathways and effectsof various operating parameters,namely temperature,H2pressure,and time,were studied to enableoptimization of the selective conversion of HMF to DMF over the Cu‐Co/Al2O3catalyst.