Ru/TiO_2催化剂上的催化湿式氧化处理H-酸废水反应性能研究

考察了反应温度、反应压力、反应气量、空速以及贵金属担载量等因素对Ru/TiO2催化剂催化湿式氧化法处理H 酸废水处理效果的影响.此外还利用X 荧光光谱(XFD)和X 射线粉末衍射(XRD)等表征手段研究了催化剂TiO2载体的杂质含量和晶型.结果表明:随着催化剂上活性组分担载量的增加,催化剂的催化活性逐步提高.在温度为240℃、压力为6.0MPa、空速为2.5h-1、气量为150mL/min的反应条件下,经过担载量为w(Ru)=3%的Ru/TiO2催化剂的催化湿式氧化处理,模型废水中的COD去除率可达到99.8%.

Ru/TiO_(2)+ZSM-5复合催化剂上糠醛和乙醇高效转化制乙酰丙酸乙酯

采用沉积还原法制备了不同载体(MO_(x)=TiO_(2)、SiO_(2)、Al_(2)O_(3)、MgO和ZrO_(2))负载的Ru催化剂,采用水热法合成了不同硅铝物质的量比(n(Si)/n(Al)=23、66、96、160和∞)的氢型ZSM-5分子筛,组成Ru/MO_(x)+ZSM-5双功能催化剂,对其在生物质平台化学品糠醛(FAL)和乙醇(EA)转化制乙酰丙酸乙酯(ELE)反应中的催化性能进行了研究。结果表明,Ru/MO_(x)+ZSM-5双功能催化剂的性能与其还原性和酸性密切相关。中等粒径的Ru纳米颗粒高度分散在TiO_(2)载体上以及Ru和TiO_(2)之间存在的强相互作用使得Ru/TiO_(2)既具有较高的FAL转化率又能抑制ELE过度加氢反应。由Ru/TiO_(2)与酸密度高的低硅铝比ZSM-5(n(Si)/n(Al)=23)混合组成的Ru/TiO_(2)+ZSM-5(n(Si)/n(Al)=23)催化剂,对FAL和EA转化制ELE具有良好的催化性能,在180℃下反应16 h,FAL转化率达96.7%,ELE收率达76.7%。此外,该双功能Ru/TiO_(2)+ZSM-5(n(Si)/n(Al)=23)催化剂也表现出良好的稳定性,重复使用多次后活性无明显降低。

Photo-enhanced thermal catalytic CO_(2) methanation activity and stability over oxygen-deficient Ru/TiO_(2) with exposed TiO_(2){001}facets:Adjusting photogenerated electron behaviors by metal-support interactions

In this study,two Ru/TiO_(2)samples with different TiO_(2)facets were prepared to investigate their photo-thermal catalytic CO_(2)+H_(2)reaction behavior.Without UV irradiation,the Ru/TiO_(2)with 67%{001}facet(3 RT)displayed improved thermal catalytic activity for CO_(2)methanation than that of Ru/TiO_(2)with 30%{001}facet(0 RT).After H_(2)pretreatment,both samples exhibited enhanced thermal catalytic activities,but the H_(2)-treated 3 RT(3 RT-H)exhibited superior activity to that of the H_(2)-treated 0 RT(0 RT-H).Under UV irradiation,3 RT-H exhibited apparent photo-promoted thermal catalytic activity and stability,but the enhanced catalytic activity was lower than that of 0 RT-H.Based on the characterization results,it is proposed that both the surface oxygen vacancies(Vos)(activating CO_(2))and the metallic Ru nanoparticles(activating H_(2))were mainly responsible for CO_(2)methanation.For 0 RT,H_(2)pretreatment and subsequent UV irradiation did not promote the formation of Vos,resulting in low catalytic activity.For 3 RT,on the one hand,H_(2)pretreatment promoted the formation of Vos,which were regenerated under UV irradiation;on the other hand,the photogenerated electrons from TiO_(2)transferred to Ru to maintain the metallic Ru nanoparticles.Both behaviors promoted the activation of CO_(2)and H_(2)and enhanced CO_(2)methanation.Moreover,the photogenerated holes favored the dissociated H at Ru migrating to TiO_(2),also promoting CO_(2)methanation.These behaviors occurring on 3 RT-H may be attributed to the suitable metal-support interaction between the Ru nanoparticles and TiO_(2){001},resulting in the easy activation of lattice oxygen in TiO_(2)to Vos.With reference to the analysis of intermediates,a photo-thermal reaction mechanism is proposed for the Ru/TiO_(2){001}facet sample.

TiO_(2) nanoparticle supported Ru catalyst for chemical upcycling of polyethylene terephthalate to alkanes

Production of fuel and chemicals from plastic waste is one of the effective ways to upcycle spent plastics,which is an interesting topic and of significance for green and sustainable development.Herein,we demonstrate a highly efficient catalyst,TiO_(2)nanoparticle supported Ru nanocatalyst(Ru/TiO_(2)),for upcycling polyethylene terephthalate(PET)to alkanes in the presence of H_(2) and water.Under the optimal conditions(200℃,60 bar H_(2),and small amount of H_(2)O),PET could completely convert into alkanes,dominated with cyclohexane and methane.It was indicated that the strong interaction between the TiO_(2)support and Ru nanoparticles made electrons flow from the TiO_(2)support to the Ru nanoparticles,which thus rendered Ru/TiO_(2)to have ability to simultaneously catalyze PET hydrolysis and intermediate hydrogenation.This work realizes the transformation of PET to alkanes,which provides a promising way to chemically upcycle PET.

钌掺杂二氧化钛制备低温选择性催化还原催化剂及其脱硝性能的研究

为得到一种具有高脱硝效率的催化剂,本研究采用溶胶凝胶法成功制备了钌(Ru)掺杂TiO_2脱硝催化剂,并对其脱硝性能进行测试,发现Ru掺杂后低温脱硝效果有明显提高。当Ru掺杂量(质量分数)为2.5%、煅烧温度为600℃时,制备出的催化剂脱硝率在270℃时可达91.67%。本文采用XRD、XPS、BET、SEM和FT-IR等手段对所制备的催化剂进行了表征。结果表明,Ru的掺杂有延缓TiO_2从锐钛矿相向金红石相转变的作用。同时,生成了具有高催化活性的RuO_2,且存在部分Ru^(4+)取代Ti^(4+),使原有晶粒尺寸发生变化,催化剂比表面积得以提高,孔隙结构得到改善,从而使催化剂表现出良好的脱硝性能。

An Integrated Carbon Dioxide Capture and Methanation Process

Reducing the ever-growing level of CO_(2)in the atmosphere is critical for the sustainable development of human society in the context of global warming.Integration of the capture and upgrading of CO_(2)is,therefore,highly desirable since each process step is costly,both energetically and economically.Here,we report a CO_(2)direct air capture(DAC)and fixation process that produces methane.Low concentrations of CO_(2)(∼400 ppm)in the air are captured by an aqueous solution of sodium hydroxide to form carbonate.The carbonate is subsequently hydrogenated to methane,which is easily separated from the reaction system,catalyzed by TiO2-supported Ru in the aqueous phase with a selectivity of 99.9%among gas-phase products.The concurrent regenerated hydroxide,in turn,increases the alkalinity of the aqueous solution for further CO_(2)capture,thereby enabling this one-ofits-kind continuous CO_(2)capture and methanation process.Engineering simulations demonstrate the energy feasibility of this CO_(2)DAC and methanation process,highlighting its promise for potential largescale applications.

易挥发臭气的催化氧化处理研究

利用含Ru0.5%的Ru/TiO2催化剂对典型易挥发臭气乙酸、氨、吡啶进行了催化氧化处理研究.结果表明:催化氧化反应极大地受温度的影响,在160～240℃范围内转化率随温度升高而升高,乙酸、氨、吡啶的最大转化率分别达到100%,85.9%,98.7%.