ZrO2对Cu/CeO2-ZrO2水煤气变换催化剂结构、性能的影响

采用共沉淀法制备了系列Cu／CeO2-ZrO2水煤气变换（WGS）催化剂。用N2物理吸附、XRD和H2-TPR手段研究了ZrO2组分对催化剂的织构、物相、还原性能、热稳定性以及WGS反应活性的影响。结果表明。添加ZrO2组分均提高了催化剂的比表面积。且随ZrO2含量的增加，孔径逐渐向小孔集中，即大孔数量减少，小孔数量增加。最可几孔径移至1．9nm左右，并逐渐增强。ZrO2的加入能有效地抑制CeO2晶粒的长大，同时适量的ZrO2可使铜铈基催化剂在WGS反应过程中保持较高的Cu分散度。从而使其具有较高的活性和稳定性。当催化剂中ZrO2含量为10％。反应温度为200℃时，WGS应中CO的转化率达到73．7％。     

Cu/TiO_2和Cu/ZrO_2催化甲醇脱氢反应的对比研究(英文)

考察了ＴｉＯ_２和ＺｒＯ_２担载的铜基催化剂的结构及其催化甲醇脱氢的反应性能。氮吸附和ＥＸＡＦＳ结果显示,两个催化剂的结构性质以及铜所处的配位环境比较接近。但Ｘ-射线光电子能谱测试结果显示,催化剂Ｃｕ／ＴｉＯ_２中铜周围的电子密度较催化剂Ｃｕ／ＺｉＯ_２中的高。ＴｉＯ_２结果表明,ＴｉＯ_２能够降低与之接触的较大ＣｕＯ的还原温度。催化剂电子结构的不同导致反应性能的差异,在Ｃｕ／ＴｉＯ_２催化剂上甲酸甲酯是主要产物,而Ｃｕ／ＺｒＯ_２催化剂则催化甲醇深度脱氢生成ＣＯ。此外,Ｃｕ／ＺｒＯ_２催化剂失活较Ｃｕ／ＴｉＯ_２催化剂慢得多。     

二硫代氨基甲酸键合硅胶对Cu2+吸附性能研究

本文以柱层层析硅胶为原料,用γ-氨丙基三甲氧基硅烷对其表面进行修饰,制得氨基键合硅胶微粒,进而在碱性条件下与二硫化碳反应,合成二硫代氨基甲酸键合硅胶(DTC-SiO2)。以Cu2+为吸附对象,考察DTC-SiO2对金属离子的吸附性能,探讨了溶液pH值、吸附剂用量、初始Cu2+浓度、吸附时间等影响材料吸附效果的因素,并研究了吸附剂对Cu2+的吸附等温线和动力学吸附特性。结果表明,在温度298K下,DTC-SiO2对Cu2+的吸附符合Langmuir等温式,准二级吸附动力学方程能够很好地描述Cu2+在DTC-SiO2上的吸附动力学行为。     

水杨酸修饰聚苯乙烯对Pb2+和Cu2+的吸附

水杨酸;聚苯乙烯;吸附;Pb2+;Cu2+     

Cu2O-SiO2纳米复合物直接催化过氧化氢的传感器研究

通过水溶液法制备一种Cu2O-SiO2纳米复合物,并将其修饰于电极表面,直接催化过氧化氢,成功制得了一种无酶的过氧化氢传感器.通过循环伏安和计时电流法考察了电极的电化学特性,发现Cu2O-SiO2对过氧化氢(H2O2)有较好的催化性能.实验结果表明,制备的传感器在H2O2浓度为3.5×l0-7 ～7.5×l0-3 mo...     

Cu2+/TiO2对甲基橙的光催化降解机理

以自制的掺铜离子的混晶型二氧化钛为光催化剂,考察了甲基橙光催化降解过程中pH值和光源的影响,提出了两种不同的光催化降解机理:在高压汞灯照射下,TiO2的价带电子被激发到导带,光生电子和空穴主要通过Cu2+ 的短路循环而复合,光催化剂的活性降低;在太阳光照射下,甲基橙发生自身光敏化氧化反应,受激电子从单线态或三线态的甲基橙分子跃迁到TiO2的导带,Cu2+起到电荷传递中继站的作用,加速了注入电子向H2O2的转移,从而促进了甲基橙的光催化降解。     

Synthesis and Structural Characterization of Cu（pic）2[CO（NH2）2]2 and （picH2）2[Cu（pic）2（SCN）2]

1 INTRODUCTION The picolinic acid (picH), also called pyridine- 2-carboxylic acid, has a broad spectrum of physio- logical effects on the activity functions of both ani- mal and plant organisms. It is attributed increasing interest due to its ability to …     

改性花生壳对Cu2+的吸附

以农林废弃物花生壳作为吸附剂对废水中的Cu2+进行吸附.结果表明,花生壳的最佳改性方法为KMnO4改性法.在50mLCu2+浓度为10mg/L的水样中,改性花生壳的最佳吸附条件为:298K下投加4mesh筛上改性花生壳0.8g,pH=5,吸附75min,此时改性花生壳对Cu2+吸附率高达96.80％.KMnO4改性花生壳对Cu2+的吸附以Langmuir方程拟合更佳.     

ZnO逆修饰小尺寸Cu/SiO2催化剂及其在CO2加氢制甲醇中的应用

Cu-ZnO is broadly used as a catalyst in CO₂ reduction to produce methanol, but fabricating small-sized Cu-ZnO catalysts with strong Cu-ZnO interactions remains a challenge. In this work, a simple, low-cost method is proposed to synthesize small-sized Cu-ZnO/SiO₂ with high activity and controllable Cu-ZnO interactions derived from copper silicate nanotubes. A series of Cu-ZnO/SiO₂ samples with different amounts of ZnO were prepared. The activities of the as-prepared catalysts for methanol synthesis were tested, and the results revealed a volcano relationship with the weight fraction of ZnO. At 523 K, the methanol selectivity increased from 20% to 67% when 14% ZnO was added to the Cu/SiO₂ catalyst, while the conversion of CO₂ increased first and then decreased with the addition of ZnO. The optimum space time yield (STY) of 244 g·kg^-1·h^-1 was obtained on C-SiO₂-7%ZnO at 543 K under 4.5 MPa H₂/CO₂. Furthermore, the synergistic effect of Cu and ZnO was studied by high resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in situ diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS), and temperature-programmed reduction (TPR) analyses. The HRTEM images showed that the Cu particles come in contact with ZnO more frequently with increased addition of ZnO, indicating that the catalysts with higher ZnO contents have a greater probability of formation of the Cu-ZnO interface, which promotes the catalytical activity of Cu-ZnO/SiO₂. Meanwhile, the HRTEM images, XRD patterns, and TPR results showed that the addition of excess ZnO leads to an increase in the size of the Cu particles, which in turn decreases the total number of active sites and further degrades the activity of the catalysts. The activation energy (E_a) for methanol synthesis and reverse water gas shift (RWGS) was calculated based on the results of the catalytical test. With the addition of ZnO, E_a for methanol synthesis decreased from 72.5 to 34.8 kJ·mol^-1, while that for RWGS increased from 61.3 to 102.7 kJ·mol^-1, illustrating that ZnO promotes the synergistic effect of Cu-ZnO. The results of XPS and in situ DRIFTS showed that the amount of Cu⁺ species decreases with the addition of ZnO, indicating that the Cu-ZnO interface serves as the active site. The Cu surface area and the turnover frequency (TOF) of methanol were calculated based on the H₂-TPR curves. The TOF of methanol on the Cu-ZnO/SiO₂ catalysts at 543 K increased from 1.5 × 10^-3 to 3.9 × 10^-3 s^-1 with the addition of ZnO, which further confirmed the promotion effect of the Cu-ZnO interface on the methanol synthesis. This study provides a method to construct Cu-ZnO interfaces based on copper silicate and to investigate the influence of ZnO on Cu-ZnO/SiO₂ catalysts.     

Ga_2O_3改性Cu/SiO_2催化剂降低水蒸气催化重整产物中CO选择性

采用蒸氨法制备的xGa-Cu/SiO_2催化剂可以同时产生Cu~0和Cu~+物种,加入Ga后催化剂的二甲醚水蒸气重整反应活性和选择性都有很大程度的提高,其中5Ga-Cu/SiO_2催化剂在380°C时的二甲醚转化率为99.8%,CO选择性为4.8%。通过透射电子显微镜(TEM),氢气-程序升温还原(H_2-TPR),N_2O滴定和X射线光电子能谱(XPS)结果发现,Ga与Cu物种之间的相互作用,一方面可以提高Cu物种的分散度,另一方面可以促进Cu~+的形成。通过改变Ga负载量可以调变Cu~+/(Cu~0+Cu~+)的比例,氢气的时空收率结果表明,Ga通过调变Cu~+/(Cu~0+Cu~+)影响催化活性,并且当Cu~+/(Cu~0+Cu~+)=0.5时,氢气时空收率达到最大值为5.02mol·g~(-1)·h~(-1)。程序升温表面反应(TPSR)结果表明,Ga通过促进水气变换反应提高反应产物CO_2选择性。     

载体表面性质对Cu/ZrO2催化剂CO加氢反应行为的影响

用XRD、LRS、NH₃-TPD、CO₂-TPD和CO-FTIR等表征手段考察了不同温度焙烧的氧化锆表面性质的差别,特别是表面酸碱性的差异对Cu/ZrO₂催化剂CO加氢反应行为的影响。结果表明,不同温度焙烧的氧化锆表面酸碱性具有较大的差异,其中以450℃焙烧的氧化锆具有较高的表面碱性和最低酸性。这些表面性质的差异对于Cu/ZrO₂催化剂的CO吸附行为产生较大的影响,进而影响CO的加氢反应活性。以450℃焙烧的氧化锆为载体时,Cu/ZrO₂催化剂具有较好的反应活性。     

CO2加氢合成甲醇Cu/ZrO2催化剂的失活因素

采用低温氮气吸脱附、X射线衍射(XRD)、电镜(TEM)以及热重差热(TG-DSC)等手段,对不同反应时间下Cu/ZrO₂催化剂的物理结构、微观形貌以及积炭情况进行了表征,分析了催化剂的失活原因。结果表明,造成催化剂失活的主要因素是活性组分烧结;其次,表面积炭覆盖其活性中心也造成催化剂活性在一定程度上的降低;而催化剂比表面积对其活性的影响较小。     

UiO-66-NH2/wood的设计构筑及高效去除水中微量重金属离子性能

矿山开采、 金属冶炼、 新型金属材料的发展以及城市供水系统老化所造成的重金属(铅、 镉、 汞、 砷、 铬、 铜及锌等)污染问题已日趋严重. 传统的水处理方法很难有效地去除低浓度的重金属污染物. 本文以天然木材为载体, 采用溶剂热合成法, 在木材三维孔道中原位合成UiO-66-NH₂金属有机框架材料(MOFs)纳米颗粒, 制备了UiO-66-NH₂/wood复合膜材料. 该复合膜材料对去除水中微量重金属离子(Hg²⁺, Cu²⁺)表现出优异的性能. 当处理速率为1.1×10² L?m^-2?h^-1时, 该复合膜材料去除水中微量重金属离子的效率仍可达到90%以上, 且处理后水中重金属离子含量低于国家饮用水标准. 这可归因于木材本身独特的三维孔道结构, 在提高水通量的同时, 还可以增加水溶液中重金属离子与MOFs颗粒的接触机会, 以及孔道内均匀分布的UiO-66-NH₂ MOFs颗粒中的—NH₂可以与重金属离子通过配位作用相结合. 该UiO-66-NH₂/wood复合膜材料还具有良好的重复利用性, 在连续6次循环使用后其去除效率无明显变化, 有望进行实际应用.     

利用ZnO@ZIF-8核壳结构构建高选择性、高稳定性的Pd/ZnO催化剂用于CO2加氢制甲醇

Catalytic CO₂ hydrogenation to methanol is a promising route to mitigate the negative effects of anthropogenic CO₂. To develop an efficient Pd/ZnO catalyst, increasing the contact between Pd and ZnO is of the utmost importance, because "naked" Pd favors CO production via the reverse water-gas shift path. Here, we have utilized a ZnO@ZIF-8 core-shell structure to synthesize Pd/ZnO catalysts via Pd immobilization and calcination. The merit of this method is that the porous outer layer can offer abundant "guest rooms" for Pd, ensuring intimate contact between Pd and the post-generated ZnO. The synthesized Pd/ZnO catalysts (PZZ8-T, T denotes the temperature of calcination in degree Celsius) is compared with a ZnO nanorod-immobilized Pd catalyst (PZ). When the catalytic reaction was performed at lower reaction temperatures (250, 270, and 290 ℃), the highest methanol space time yield (STY) and highest STY per Pd achieved by PZ at 290 ℃ were 0.465 g g_cat^-1 h^-1 and 13.0 g g_Pd^-1 h^-1, respectively. However, all the PZZ8-T catalysts exhibited methanol selectivity values greater than 67.0% at 290 ℃, in sharp contrast to a methanol selectivity value of 32.8% for PZ at the same temperature. Thus, we performed additional investigations of the PZZ8-T catalysts at 310 and 360 ℃, which are unusually high temperatures for CO₂ hydrogenation to methanol because the required endothermic reaction is expected to be severely inhibited at such high temperatures. Interestingly, the PZZ8-T catalysts were observed to achieve a methanol selectivity value of approximately 60% at 310 ℃, and PZZ8-400 was observed to maintain a methanol selectivity value of 51.9% even at a temperature of 360 ℃. Thus, PZZ8-400 attains the highest methanol STY of 0.571 g g_cat^-1 h^-1at 310 ℃. For a better understanding of the structure-performance relationship, we characterized the catalysts using different techniques, focusing especially on the surface properties. X-ray photoelectron spectroscopy (XPS) results indicated a linear relationship between the methanol selectivity and the surface PdZn : Pd ratio, proving that the surface PdZn phase is the active site for CO₂ hydrogenation to methanol. Furthermore, analysis of the XPS O 1s spectrum together with the electronic paramagnetic resonance results revealed that both, the oxygen vacancy as well as the ZnO polar surface, played important roles in CO₂ activation. Chemisorption techniques provided further quantitative and qualitative information regarding the Pd-ZnO interface that is closely related to the CO₂ conversion rate. We believe that our results can provide insight into the catalytic reaction of CO₂ hydrogenation from the perspective of surface science. In addition, this work is an illustrative example of the use of novel chemical structures in the fabrication of superior catalysts using a traditional formula.     

NaBH4处理LaCuZnX(X=Zr、Al、Zr+Al)(类)钙钛矿型催化剂及其CO2加氢合成甲醇性能的研究

采用共沉淀法分别制备了不同F-T组分(Fe、Co、Ni)改性的KCuZrO_2催化剂,并用于催化CO加氢合成异丁醇。通过BET、XRD、TEM、XPS、H_2-TPR、CO-TPD以及in-situ DRIFTS对催化剂进行了表征。结果显示,F-T组分的加入促进了乙醇和丙醇的形成,但是对异丁醇选择性影响不同。结果表明,Fe促进了催化剂中各组分的分散,活性组分Cu在催化剂表面发生了富集,提高了H_2/CO活化吸附;另外,KFeCuZrO_2的催化剂表面含有较多的C_1物种,有利于乙醇和丙醇进一步发生β-加成反应得到异丁醇,而Co和Ni改性的催化剂上缺少足够的C_1物种,因此,异丁醇的选择性并未明显增加。Co的引入对催化剂结构以及Cu的分散影响不大,但是Co改性后催化剂性能有所下降,其原因是催化剂发生了失活;Ni添加后催化剂比表面积有所减小,且催化剂表面Cu/Zr物质的量比也降低到0.19,催化剂粒径增大,Cu-Zr之间相互作用减弱,异丁醇选择性降低。     

Cu/ZrO_2催化剂的结构及其CO_2加氢合成甲醇催化反应性能

采用低温氮气吸脱附、XRD、TPR、In-situ IR和XPS等表征手段,对分步沉淀法、浸渍沉淀法和固态反应法制备的CuO/ZrO2催化剂进行表征,同时考察了其CO2加氢合成甲醇反应性能。结果表明,制备方法对CuO/ZrO2的物理结构和还原性能影响很大,其中浸渍沉淀法制备的催化剂Cu与ZrO2相互作用最强,并显示了较高的CO2转化率和甲醇收率。Cu与ZrO相互作用的强弱直接影响CO加氢合成甲醇反应性能的优劣,而催化剂的比表面积不是影响反应性能的主导因素。     

Cu/ZnO催化糠醛气相加氢制2-甲基呋喃的研究

通过共沉淀法制备一系列铜锌催化剂,用于固定床上糠醛气相加氢制2-甲基呋喃的研究。采用X射线衍射仪(XRD)、N_2吸附-脱附、扫描电子显微镜(SEM)、H_2-程序升温还原(H_2-TPR)、NH_3-程序升温脱附(NH_3-TPD)表征,分析催化剂中Cu0和ZnO在催化反应中的作用。结果表明,Cu~0是糠醛加氢的活性中心,氧化锌的加入减小了催化剂晶粒粒径、增大了催化剂比表面积、利于催化剂还原和增加催化剂表面弱酸性位。当Cu/Zn物质的量比为1∶2时,Cu_1Zn_2催化剂具有适宜氧化还原活性中心及弱酸位数量,对2-甲基呋喃表现出较高的选择性。Cu_1Zn_2催化剂在常压、反应温度为200℃、氢醛物质的量比为4∶1、糠醛体积空速为0.3 h-1条件下,糠醛转化率100.0%,2-甲基呋喃选择性最高为93.6%。反应稳定运行200 h后,糠醛转化率仍为100.0%,2-甲基呋喃选择性为80.0%,糠醇选择性为11.4%。     

CaO对Cu-ZnO-ZrO_2催化CO_2加H_2合成甲醇性能影响

用CaO作为改性助剂,采用并流共沉淀法制备了CuO∶ZnO∶ZrO_2为5∶4∶1(物质的量比),CaO添加量为0、1%、2%、4%、8%、16%(摩尔分数)的六组催化剂。用X射线衍射(XRD)、微商热重(TG-DTG)、傅里叶红外(FT-IR)、N2吸附脱附(BET)、X射线光电子能谱(XPS)、氢气程序升温还原(H_2-TPR)、CO_2程序升温脱附(CO_2-TPD)、NH_3程序升温脱附(NH_3-TPD)对催化剂进行了表征。用自制固定床评价了催化剂活性。结果表明,添加CaO后,催化剂路易斯酸性和表面碱性增强;催化剂母体中高温碳酸盐含量增加,热稳定性增强,CuO颗粒粒径变小,Cu-Zn协同作用增强,Cu比表面积增大,分散性变好。催化剂活性受到表面酸碱性、铜比表面积、Cu-Zn协同作用和铜分散性共同影响。当CaO为2%时,铜比表面积为79.3 m2/g、铜分散度为34.8%、CO_2转化率为24.55%、甲醇选择性为19.01%、甲醇收率为0.044 g/(gcat·h),催化剂活性最好。过量CaO占据催化剂孔道和覆盖表面活性位,使催化剂路易斯酸性和表面碱性过强,CuO与H_2有效接触减少,CO_2难以脱附,催化活性下降。因此,适量CaO(2%)添加可促进CO_2加氢反应合成甲醇。