小麦粉基镶嵌式钌炭催化剂的制备及苯甲酸水相加氢性能

以小麦粉为碳源,纳米氧化硅球为模板,通过固相研磨法混合,直接炭化制备了镶嵌式钌炭催化剂(Ru-SC),通过氮气物理吸附、CO静态化学吸附、X射线粉末衍射(XRD)和透射电镜等表征。结果表明,Ru-SC具有介孔结构,钌纳米粒子均匀镶嵌于小麦粉炭中。同时研究了其催化苯甲酸水相加氢的反应性能,发现具有中孔和镶嵌式结构的Ru-SC在苯甲酸加氢反应中具有优异的催化活性,在120℃,氢气压力为4 MPa的条件下,转化频率达524 h^-1;经过5次套用实验后转化率没有明显下降,表现出良好的稳定性。该方法利用原料丰富的小麦粉为碳源,制备工艺简单,成本低,在负载型金属催化剂的制备中具有广阔的应用前景。

钌炭催化剂用于麦芽糖加氢制备麦芽糖醇的研究

使用钌炭催化剂,由麦芽糖加氢制备麦芽糖醇,确定pH值、催化剂添加量、压力、温度、反应时间五个因素对该反应的影响。结果表明:当pH值为8.0,催化剂添加量0.1%,反应压力4MPa,反应温度110℃,反应时间120min时,麦芽糖转化率为98.2%。

电感耦合等离子体发射光谱法测定钌炭催化剂中的钌

对测定钌炭催化剂中钌质量分数的方法进行了试验研究,确定了氢氧化钾碱熔、盐酸浸取的溶样方式,对电感耦合等离子体发射光谱法和原子吸收分光光度法测定钌炭催化剂中钌的质量分数进行了对比分析,结果表明:电感耦合等离子体发射光谱法的测定结果更接近实际值,原子吸收分光光度法测定结果偏低。对电感耦合等离子体发射光谱法进行了准确度、精密度的测定,结果表明:该方法相对标准偏差为0.59%,加标回收率为95.90%~101.30%,具有较好的准确度和精密度,可用于测定钌炭催化剂中钌的质量分数。

钌炭催化剂表面改性及在苯酚加氢反应的应用

通过软模板法成功在镶嵌式钌炭催化剂Ru-OMC表面包覆介孔二氧化硅,研究了催化剂在苯酚加氢反应中的应用,采用N2物理吸附、扫描透射电镜等手段对催化剂进行了系统的表征。结果表明,介孔二氧化硅包覆层改变了催化剂的亲水性质,使得原本疏水性质的Ru-OMC表面变成了亲水性质,提高了环己烷-水2相体系中苯酚加氢反应的转化频率及分离效率。

负载型钌炭加氢催化剂的工艺研究

通过对负载型钌炭催化剂的制备工艺的研究,分析讨论了载体种类、制备工艺中的负载和还原操作对钌炭催化剂性能的影响。研究结果表明:在催化剂的制备过程中,活性炭载体、负载方式和还原操作对表面活性金属的分散度有影响,从而造成催化剂的性能差异。选择椰壳炭为载体、沉淀法进行活性金属的负载,经过液相法硼氢化钠还原得到的催化剂表面活性金属的分散度高,催化剂在苯部分加氢反应中具有高活性和高选择性,环己烯的收率达到55%。

钌钯/炭催化剂催化苯甲酸加氢制备环己基甲酸

对钌钯/炭催化剂催化苯甲酸加氢制备环己基甲酸进行研究,考察金属负载量、溶剂用量、反应温度和反应压力对反应的影响,并考察催化剂重复使用性能。结果表明,使用自制的钌钯/炭催化剂,催化剂中金属钌纳米粒子和钯纳米粒子负载质量分数分别为5.0%和0.5%、m(苯甲酸)∶m(环己基甲酸)=2∶1、反应温度(135~145)℃和反应压力(4~5)MPa条件下,苯甲酸转化率≥99.3%,环己基甲酸选择性≥99.0%。催化剂重复使用16次,仍具有较高活性。

A highly stable and active mesoporous ruthenium catalyst for ammonia synthesis prepared by a RuCl_3/SiO_2-templated approach

Molecular nitrogen is relatively inert and the activation of its triple bond is full of challenges and of significance.Hence,searching for an efficiently heterogeneous catalyst with high stability and dispersion is one of the important targets of chemical technology.Here,we report a Ba‐K/Ru‐MC catalyst with Ru particle size of 1.5–2.5 nm semi‐embedded in a mesoporous C matrix and with dual promoters of Ba and K that exhibits a higher activity than the supported Ba‐Ru‐K/MC catalyst,although both have similar metal particle sizes for ammonia synthesis.Further,the Ba‐K/Ru‐MC catalyst is more active than commercial fused Fe catalysts and supported Ru catalysts.Characterization techniques such as high‐resolution transmission electron microscopy,N2 physisorption,CO chemisorption,and temperature‐programmed reduction suggest that the Ru nanoparticles have strong interactions with the C matrix in Ba‐K/Ru‐MC,which may facilitate electron transport better than supported nanoparticles.

Formation mechanism of highly dispersed semi-embedded ruthenium nanoparticles in porous carbon matrix determined by in situ temperature-programmed infrared spectroscopy

The carbonization process of a sucrose‐RuCl3/SBA‐15composite towards a Ru‐containing ordered mesoporous carbon(Ru‐OMC)catalyst was studied by in situ temperature‐programmed infrared spectroscopy to identify the stabilization role of organic carbon precursors during the formation of highly dispersed Ru nanoparticles.The results show that the formation of metal carbonyl species results in the formation of homogeneously distributed Ru nanoparticles,and the rigid silica support and carbon matrix around the Ru(CO)x complex can significantly avoid the sintering and agglomeration of Ru metal particles during elevated temperature thermal treatment.These results ultimately demonstrate that sucrose plays important roles in the formation of homogeneously distributed Ru nanoparticles in a porous carbon matrix.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.