权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Novel functions of composite catalysts derived from Pd and support metal oxides-mechanism and utilization

Pd与载体金属氧化物复合催化剂的新功能-机理与应用

基本信息

批准号：
07650932
负责人：
TAKEZAWA Nobutsune
金额：
$ 1.66万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650932/
关键词：
Pd ZnO Steam reforming of methanol Dehydrogenation of methaniol Methyl formate Pd-Zn alloy PtZn alloy Novel alloy catalysts Pd-3B金属合金 Pt-3B金属合金 PdZn合金 PtZn合金 ZnO触媒 ZnO担持触媒

项目摘要

Pd/ZnO exhibited anomalously high catalytic performance for the steam reforming of methanol and the dehydrogenation to HCOOCH_3 among various supported Pd ctalysts. The selectivities for the steam reforming and the dehydrogenation to HCOOCH_3 were achieved at 99.5% and 80%, respectively. In contraast, the other supported Pd catalysts showed the selectivities of 0-40% and 0%, respectively for the steam reforming and the dehydrogenation to HCOOCH_3. The catalytic performance of Pd/ZnO for the steam reforming and the dehydrogenation was greatly improved by previously reducing the catalyst at higher temperatures. The increased catalytic performace was attributed to PdZn alloys formed in the previous reduction of the catalyst. By XP spectroscopy, it was revealed that electron transfer took place from Pd to Zn in the formation of PdZn alloys. Over the alloyed catalysts, formaldehyde species formed in the reactions were effectively attacked by -OH or CH_3O-, being transformed into CO_2 and H_ … More 2 or HCOOCH_3. Over the other catalysts containing unalloyed Pd, the formaldehyde species decomposed selectively to CO and H_2 in the steam steam reforming and the dehydrogenation of methanol. It was suggested that formaldehyde species were stabilized on positively charged Pd sites in eta^1 (O) -form in the reactions over PdZn alloys, and subjected to the nucleophilic addition of -OH or CH_3O-. On the basis of the proposed mechanism of the generation of new catalytic function of Pd, novel Pd_<3.1>Zn_<6.9> and PtZn alloy catalysts were developed. These alloys showed high selectivity for the dehydrogenation of methanol to HCOOCH_3 as well as the steam reeforming. Experimemts were carried out over Pd/ZnO catalysts prepared by various preparation methods. Pd/ZnO (10wt% Pd) obtained by precipitation of Pd (II) and Zn (II) with a Na_2CO_3 solution exhibited best performance for the steam reforming among the Pd catalysts so far studied. The activity of Pd/ZnO was twice that for Cu/SiO_2 (30wt% Cu) previously studied. Less

在各种负载型Pd催化剂中，Pd/ZnO催化剂对甲醇水蒸气重整和HCOOCH3脱氢反应表现出异常高的催化性能。水蒸气重整和脱氢制HCOOCH3的选择性分别达到99.5%和80%。与之相比，其他负载型Pd催化剂对水蒸气重整和脱氢制HCOOCH3的选择性分别为0-40%和0%。通过在较高温度下预先还原催化剂，Pd/ZnO催化剂对水蒸气重整和脱氢反应的催化性能有了很大的提高。催化剂催化性能的提高归功于催化剂在前一次还原过程中形成的PdZn合金。X射线能谱分析表明，在Pd-Zn合金的形成过程中，Pd-Zn之间发生了电子转移。在合金催化剂上，反应中形成的甲醛物种被-OH或CH3O-有效地攻击，转化为CO2和H_…在其他含Pd的催化剂上，甲醛物种在水蒸气重整和甲醇脱氢反应中选择性地分解为CO和H_2。结果表明，在PdZn合金上的反应中，甲醛物种以ETA^1(O)形式稳定在带正电的Pd中心上，并受到-OH或CH3O-亲核加成的影响。在已提出的Pd产生新催化作用机理的基础上，开发了新型Pd_lt；3.1&gt；Zn_&lt；6.9&gt；和PtZn合金催化剂。这些合金对甲醇脱氢制HCOOCH3和水蒸气再生成均表现出较高的选择性。对不同制备方法制备的Pd/ZnO催化剂进行了实验研究。用Na2CO3溶液沉淀Pd(II)和Zn(II)得到的Pd/ZnO(10wt%Pd)催化剂是目前所研究的Pd催化剂中水蒸气重整反应性能最好的催化剂。Pd/ZnO催化剂的活性是以前研究的Cu/SiO_2(30wt%Cu)的两倍。较少