Pt/Co和Pt/Ni双金属纳米溶胶制备及催化制氢

采用化学共还原法制备聚乙烯吡咯烷酮(PVP)稳定的Pt/Co和Pt/Ni双金属纳米溶胶,采用UV-Vis、TEM等对所合成的Pt/Co和Pt/Ni双金属纳米溶胶进行表征,研究了化学组成对双金属纳米溶胶催化剂催化NaBH4水解制氢的影响. 结果表明,所制双金属纳米溶胶的平均粒径约为2.0 nm,双金属纳米溶胶的催化能力高于单金属Pt, Co, Ni纳米溶胶,Pt/Co和Pt/Ni双金属纳米颗粒优异的催化性能可归因于电荷转移效应,Co或者Ni原子与Pt原子之间发生的电荷转移效应使得Pt原子带负电而Co或者Ni原子带正电,荷电的Pt和Co、Ni原子成为催化反应的活性中心,促进了催化反应的进行.     

电辅助下非晶态Co-Ni-Fe对五氯苯酚的加氢脱氯

采用化学还原法制备了非晶态Co-Ni-Fe三元催化剂,通过改变金属盐的比例制得不同Co含量的复合催化剂。分析了催化剂的特征,并在电辅助体系下考察了对五氯苯酚(PCP)的催化加氢脱氯性能。结果表明,Ni-Fe催化剂中,Co的引入有效地提高了水中PCP的加氢脱氯效率。当Co、Ni、Fe物质的量比为0.5∶0.5∶9,电位为-0.2 V,硫酸浓度为0.2 mol/L,催化剂投加量为4 g/L时,脱氯率达到90%。从产物分析可知,PCP最终完全脱氯为苯酚。     

Ir-MOx/Al2O3催化剂上硝基芳烃加氢性能研究

采用正丁基锂快速还原法合成了双金属IrM(M=Ni、Fe和Co)纳米颗粒,并以其为前体在氧化铝载体上经过原位煅烧和选择性还原,制得具有明确Ir-MOx杂化界面结构的Ir-MOx/Al2O3催化剂.结果表明,相比Ir/Al2O3催化剂,Ir-MOx/Al2O3在对氯硝基苯和对硝基苯乙酮选择性加氢制备氨基芳烃的反应中均展现...     

Pd/Fe双金属对1,2,4-三氯苯的催化脱氯

采用Pd/Fe双金属体系对1,2,4-三氯苯（1,2,4-TCB）进行了快速催化还原脱氯的研究.结果表明,在钯的催化作用下,零价铁对1,2,4-TCB有较好的还原脱氯效率.当Pd/Fe双金属的钯化氯为0.06%时,催化剂用量为1g/40mL,反应1h后TCB的脱氯率可达99%.反应速率随钯化氯的提高而增加.反应在Pd/Fe表面进行,符合准一级反应,反应速率常数为0.0837min-1.TCB在催化脱氯的过程中先脱氯成为DCB,再依次脱氯为氯苯和苯.     

载体对非晶态催化剂的氯代硝基苯加氢性能影响

以纳米碳管(CNTs)、γ-Al2O3、活性炭(AC)、SiO2为载体,Pt、Sn为活性组分,采用浸渍-化学还原法制备了负载Pt-Sn双金属非晶态催化剂,采用XRD、SEM、SAED、EDS等技术手段对催化剂进行了表征,明确了催化剂的非晶态性质、结构形态、粒子大小和元素组成等.以氯代硝基苯液相加氢为目标反应,对各催化剂的催化性能进行了评价.结果表明负载Pt-Sn非晶态催化剂在氯代硝基苯加氢反应中具有较好的活性和良好的选择性,其中以CNTs为载体的非晶态催化剂可使三种氯代硝基物加氢转化率达到99.9%,加氢脱氯率小于1.2%.从载体的微观结构、金属-载体相互作用、活性组分在载体表面的几何效应和电子效应等方面对载体响氯代硝基苯加氢性能进行了讨论.     

双金属Co/Pd纳米催化剂催化乙炔双羰化反应的性能研究

采用一步还原法制备了一系列双金属纳米Pd基合金催化剂,以获得优秀的乙炔双羰化反应催化剂。利用透射电子显微镜(TEM)、X-射线光电子能谱(XPS)、X-射线衍射(XRD)、原位红外光谱(In-situ IR)等手段对催化剂的性质进行了研究。考察了掺杂金属、溶剂、助剂种类及用量、一氧化碳压力、温度对反应产率的影响。结果表明:以乙腈为溶剂,乙炔、一氧化碳和甲醇为原料合成丁烯二酸二甲酯,Co/Pd双金属纳米催化剂的活性最高,在低温低压条件下丁烯二酸二甲酯的总产率可达97.99%。Co元素的引入,有助于降低Pd对一氧化碳吸附强度,使更多的吸附于催化剂表面的CO分子能参与反应,提高了Pd基纳米双金属催化剂催化乙炔双羰化反应的活性。     

Ni-B非晶态合金催化加氢制备氯代苯胺

采用水合肼和硼氢化钾为共还原剂,适当比例的甲醇、乙醇和水的混合物为溶剂,在333 K下制得负载催化剂P1。XRD、TEM、SAED测定结果表明,该催化剂是一种纳米级非晶态合金。将P1催化剂用于邻氯硝基苯加氢反应,在底物100%转化时,生成邻氯苯胺的选择性达到94.3%。对一系列氯代硝基芳烃化合物在P1催化剂上的催化加氢反应进行了考察,得出脱氯顺序依次为:2-氯-5-硝基甲苯>邻氯硝基苯>间氯硝基苯=对氯硝基苯>2,5-二氯硝基苯,分析了不同氯代硝基苯的结构与脱氯的关系,认为在该催化剂上脱氯的主要原因,是生成的氯代苯胺在催化剂表面的吸附。讨论了金属添加剂(Cr、Mn、Fe、Co、Cu、Mo、Zn、La)对P1催化剂催化加氢制备邻氯苯胺的影响,发现添加Cu、Fe能提高催化剂的选择性,在底物基本转化时,选择性由不加金属添加剂时的94.3%,分别提高到97.2%和97.6%。     

Co、Mn、Ni纳米粒的制备及其对联氨的催化氧化性能研究

采用浸渍-液相还原法,分别制备了纳米Co、Ni、Mn催化剂,以泡沫镍为集电体,以不同材料作为载体制备电极。采用极化曲线测试了不同催化剂对联氨氧化的催化性能。结果表明,Co和Ni对联氨氧化有明显的催化效果,而Mn基本没有催化效果,Co和Ni相比较,在-0.8 V电位下,Co的电流密度为175 mA/cm2,Ni的达到250 mA/cm2,可见Ni对联氨的氧化反应有较好的催化作用。同时,Vulcan XC-72作为催化剂载体更有助于提高催化剂性能。     

助剂Mo对硅柱撑蒙脱土负载镍催化剂结构及加氢脱氧性能的影响

以聚乙烯吡咯烷酮为纳米颗粒保护剂,水合联氨为还原剂,采用液相还原法制备硅柱撑蒙脱土负载型双金属催化剂Mo-Ni/SPC,通过XRD、N2吸附-脱附、HRTEM、FT-IR和XPS等研究助剂Mo添加量对催化剂结构的影响。以苯酚加氢脱氧为探针反应对Mo-Ni/SPC催化剂性能进行评价,研究催化反应的最佳工艺条件及重复使用性能。结果表明,在3 MPa和623 K条件下,Mo-Ni/SPC催化剂表现出优异的催化性能,苯酚转化率98%,环己烷选择性约95%,脱氧率100%。     

Ni-Co双金属催化剂应用于CO_2甲烷化的研究

以Al_2O_3为载体,采用共浸渍法制备Ni-Co双金属催化剂,研究了Ni-Co摩尔比对CO_2甲烷化催化研究影响。分别采用低温氮气吸附脱附、X射线衍射、CO_2化学吸附、H_2-TPD、H_2-TPR对催化剂进行表征,结果表明,Co的加入对催化剂表面的酸碱性和Ni晶粒尺寸没有显著影响,但却显著提高了催化剂的催化性能,通过在线检测发现,加入Co后催化剂的二氧化碳的裂解温度显著降低,说明Co的加入显著降低了反应的活化能,提高了催化剂的性能。     

纳米钯金铁三金属催化剂的制备及其对三氯乙烯的降解

在乙醇-水体系中利用硼氢化物液相还原法合成纳米铁颗粒,通过化学沉淀法将钯金粒子负载于纳米铁表面,得到纳米钯金铁(Pd-Au@Fe)三金属催化剂复合材料,采用TEM, EDS和XPS对其进行表征. 结果表明,与纳米单金属Fe0及双金属Pd@Fe相比,三金属催化剂对三氯乙烯(TCE)具有更高的降解能力. 保持催化剂加量1.4 g/L, Pd/Fe为0.35%(w), Au/Fe为1.0%(w)时,其降解15 mg/L TCE的速度最快,5 min时去除率为88.21%,表观速率常数为0.311 min-1,是相同Pd含量下Pd@Fe双金属催化剂的3.6倍. 随降解反应持续,Pd-Au@Fe的乙烯乙烷生成率及乙烯加氢转换乙烷速率均远高于双金属Pd@Fe.     

Effects of iron precursors on the structure and catalytic performance of iron molybdate prepared by mechanochemical route for methanol to formaldehyde

Mechanochemical synthesis has been applied for many novel material preparations and gained more and more attention due to green and high-efficiency recently. In order to explore the influences of iron precursors on structure and performance of iron molybdate catalyst prepared by mechanochemical route, three typical and cheap iron precursors have been used in preparation of iron molybdate catalyst. Many characterization methods have been employed to obtain the physical and chemical properties of iron molybdate catalyst. Results indicate that iron precursors have the significant impact on the phase composition, crystal morphology and catalytic performance in the conversion of methanol to formaldehyde. It is hard to regulate the phase composition by changing Mo/Fe mole ratios for Fe_2(SO_4)_3 as iron precursor. In addition, as for Fe_2(SO_4)_3, the formaldehyde yield is lower than that from iron molybdate catalyst prepared with Fe(NO_3)_3·9H_2O due to the reduction in Fe_2(MoO_4)_3 phase as active phase. Based on mechanochemical and coprecipitation method, the solvent water could be a key factor for the formation of MoO_3 and Fe_2(MoO_4) for FeCl_3·6H_2O and Fe_2(SO_4)_3 as precursors. Iron molybdate catalyst prepared with Fe(NO_3)_3·9H_2O by mechanochemical route, shows the best methanol conversion and formaldehyde yield in this reaction.     

The role of Fe on PtPd oxidation catalyst prepared by simultaneous and sequential incipient wetnesses

The roles and effects of Fe on the catalytic performance and physicochemical properties of a PtPd diesel oxidation catalyst prepared by three different methods were investigated by CO oxidation reaction, X-ray diffraction, temperature-programmed reduction (TPR), temperature-programmed oxidation, and BET surface area. It was found that the roles of Fe depended strongly on the sequential order of Fe introduction during the preparation of the PtPd catalyst. The Fe/PtPd/Al₂O₃ catalyst was prepared by introducing Fe onto the PtPd/Al₂O₃, and the PtPd/Fe/Al₂O₃ catalyst was obtained by loading the PtPd onto the Fe/Al₂O₃. The former had a superior activity. From the TPR results, the catalytic activity of CO oxidation was correlated with the oxygen mobility of the iron oxides. For PtPd/Fe/Al₂O₃, the iron interacted preferentially with the alumina support forming FeAlO₃, which resulted in the stabilization of the support and a reduction in the surface area. The major role of Fe was to promote the enhancement of the catalytic activity of PtPd through an intimate interaction between the PtPd and iron oxides, which had lattice oxygens to generate oxygen with oxidation abilities.     

过渡金属改性的Pt/n-Al_2O_3在肉桂醛加氢反应中的催化性能

用NaBH4作还原剂,制备了中性氧化铝(n-Al2O3)负载的Pt-M(M=Fe,Co,Ni,Cu,Mn,Sn)双金属催化剂。考察了过渡金属及反应条件对Pt-M/n-Al2O3催化肉桂醛加氢制肉桂醇的影响。结果表明,Fe改性的Pt/n-Al2O3对催化肉桂醛加氢制肉桂醇具有较好的催化性能,当Pt-Fe/n-Al2O3(中性)催化剂中Pt、Fe的含量均为0.3%时,在70℃,2 MPa氢气条件下反应1.5 h,肉桂醛的转化率为100%,肉桂醇选择性高达84.8%。     

反应条件对钌催化剂和铁催化剂的氨合成性能影响

Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared,and the influences of reaction temperature,space velocity,pressure,and H2/N2 ratio on performance of iron catalyst coupled with Ru catalyst in series for ammonia synthesis were investigated.The activity tests were also performed on the single Ru and Fe catalysts as comparison.Results showed that the activity of the Ru catalyst for ammonia synthesis was higher than that of the iron catalyst by 33.5%-37.6% under the reaction conditions:375-400 °C,10 MPa,10000 h-1,H2︰N2 3,and the Ru catalyst also had better thermal stability when treated at 475 °C for 20 h.The outlet ammonia concentration using Fe-Ru catalyst was increased by 45.6%-63.5% than that of the single-iron catalyst at low tem-perature (375-400 °C),and the outlet ammonia concentration increased with increasing Ru catalyst loading.     

过渡金属改性的Pt／n-Al2O3在肉桂醛加氢反应中的催化性能

用NaBH4作还原剂,制备了中性氧化铝（n-Al2O3）负载的Pt-M（M=Fe,Co,Ni,Cu,Mn,Sn）双金属催化剂。考察了过渡金属及反应条件对Pt-M／n·Al2O3催化肉桂醛加氢制肉桂醇的影响。结果表明,Fe改性的Pt／n-Al2O3对催化肉桂醛加氢制肉桂醇具有较好的催化性能,当Pt-Fe／n—Al2O3（中性）催化剂中Pt、Fe的含量均为0．3％时,在70℃,2MPa氢气条件下反应1．5h,肉桂醛的转化率为100％,肉桂醇选择性高达84．8％。     

Pd/Fe对-二氯苯的催化脱氯及其动力学

o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water through catalytic reduction. The dechlorination reaction is believed to take place on the surface site of the catalyst via a pseudo-first-order reaction. The final reduction product of o-DCB is benzene. The dechlorination rate increases with the increase of bulk loading of palladium due to the increase of both the surface loading of palladium and the total surface area. Dechlorination efficiency accounts for 90% at Pd/Fe mass ratio 0.02% and metal to solution ratio about 53.3g-L-1 in 120 minutes. Dechlorination is affected by the reaction temperature, pH, Pd/Fe ratio and the addition of Pd/Fe. Ea is found to be 102.5kJ.mol-1 in the temperature ra,nge of 287-313K.     

The effect of cobalt on the activation of fused iron catalyst for ammonia synthesis

BET, scanning electron microscopy, X-ray diffraction, Mössbauer spectroscopy, X-ray fluorescence spectroscopy and McBain thermobalance were used to investigate the effect of cobalt on the reduction behavior and activity of used iron catalyst for ammonia synthesis. Activity tests were carried out under 10 MPa in the 350–450°C temperature rang. Studies were performed on the traditional multipromoted iron catalyst and on the series of catalysts prepared with addition of cobalt. Addition of cobalt promoted the iron catalyst for ammonia synthesis. The most active sample was that containing approx. 5.5% wt Co. Cobalt changed the reduction behavior of the catalyst. The rate of the surface change during reduction was higher for the case of the ‘cobalt catalyst’; however the rate of mass change was higher for a typical iron catalyst. The process of reduction was probably followed by the formation of an Fe₃Co compound and by the surface faceting, with the exposure of an Fe(111) plane.     

Fe-Ce/SiO2固体碱催化剂用于制备碳酸二甲酯

采用化学还原法制备亚价负载铁催化剂,通过空气氧化为Fe³⁺碱性活性中心。考察了该催化剂在碳酸丙烯酯与甲醇酯交换制备碳酸二甲酯反应中的活性和选择性。采用N₂吸附-脱附、TEM、XRD、XPS和CO₂-TPD等对所制备的催化剂进行了表征。结果表明：催化剂的表面结构与碱性是影响其活性的重要因素。相对于Fe或Ce单金属催化剂,Fe-Ce/SiO₂催化剂的碱量大幅度提升,且Fe与Ce通过相互作用形成了稳定的非晶态结构。在醇酯比为15∶1、反应温度为140℃、催化剂用量为反应物总质量的0.5%、 Ce/Fe原子比为2∶1的反应条件下,碳酸丙烯酯转化率为88%,碳酸二甲酯的选择性为92%。催化剂在循环使用10次之后,其活性保持不变。     

Hydrogen Production by Catalytic Hydrolysis of Sodium Borohydride with a Bimetallic Solid-State Co-Fe Complex Catalyst

The addition of the active non-noble metal species on a ligand can influence the catalytic performance of catalyst. In the present work, a new bi-metallic solid-state complex catalyst system, including 4-4’-methylene bis(2,6-diethyl) aniline-3,5-di-tert-butylsalisilaldimin ligand and Fe and Co metal salts are prepared for hydrogen generation by catalytic hydrolysis of NaBH₄. It was found that the Co/Fe mixture ratio, temperature, NaBH₄, and NaOH concentrations, all exert considerable influence on the catalytic effectiveness of Co–Fe complex catalyst towards the hydrolysis reaction of NaBH₄. The results suggested that the optimal mixture percentage of Co–Fe complex catalyst is 80:20. The obtained complex catalysts are characterized by XRD, FT-IR, and SEM techniques.