催化学报 ›› 2016, Vol. 37 ›› Issue (9): 1513-1520.DOI: 10.1016/S1872-2067(16)62479-8

• 论文 • 上一篇    下一篇

助剂对铂-钨催化剂体系催化氢解甘油制1,3-丙二醇性能的影响

王佳a,b, 雷念a,b, 杨超军a,b, 苏杨a, 赵晓晨a, 王爱琴a   

  1. a. 中国科学院大连化学物理研究所催化基础重点实验室, 辽宁大连 116023;
    b. 中国科学院大学, 北京 100084
  • 收稿日期:2016-04-05 修回日期:2016-05-27 出版日期:2016-09-21 发布日期:2016-09-21
  • 通讯作者: Xiaochen Zhao, Aiqin Wang
  • 基金资助:

    国家自然科学基金(21176235,21373206,21303187).

Effect of promoters on the selective hydrogenolysis of glycerol over Pt/W-containing catalysts

Jia Wanga,b, Nian Leia,b, Chaojun Yanga,b, Yang Sua, Xiaochen Zhaoa, Aiqin Wanga   

  1. a. State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
    b. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2016-04-05 Revised:2016-05-27 Online:2016-09-21 Published:2016-09-21
  • Contact: Xiaochen Zhao, Aiqin Wang
  • Supported by:

    This work was supported by the National Natural Science Foundation of China(21176235, 21373206, 21303187).

摘要:

甘油作为生物柴油产业的副产物大量过剩,通过甘油氢解制备具有高附加值的丙二醇既符合原子经济的原则,又具有重要的学术意义和应用价值.尤其是选择氢解制得1,3-丙二醇,因其产物在新型聚酯材料合成中不可替代的作用而备受关注,被认为是最具工业应用潜力的甘油转化工艺之一.目前,可高选择性制得1,3-丙二醇的催化剂体系主要是为铱-铼催化剂和铂-钨催化剂两类.前期工作表明,氧化钨担载的铂单原子/准单原子催化剂(Pt/WOx)具有优异的低压活性(1 MPa氢气)和1,3-丙二醇时空收率.然而在该温和条件下,催化产物仍然以过度氢解的产物正丙醇为主.一般来讲,引入助剂可以通过改变活性组分的电子结构、覆盖不利反应位点、调变载体表面化学性质等来改变催化剂的催化活性、选择性和稳定性.我们以单原子/准单原子催化剂Pt/WOx和担载型催化剂Pt/WOx/Al2O3为催化剂母体,引入过渡金属和贵金属助剂,考察助剂对氢解反应活性和选择性的影响,并对比有无氧化铝载体时助剂对反应活性的影响.对于Pt/WOx体系,La和Fe的引入有助于甘油转化率和1,3-丙二醇选择性的提高,同时也明显地提高了催化剂的稳定性.其中0.1% La是最佳引入量.然而,对于担载型催化剂Pt/WOx/Al2O3,La的引入在提高1,3-丙二醇选择性的同时,甘油的转化率也有一定程度下降.但由于Pt/WOx/Al2O3催化剂的本征活性较高,通过加入助剂提高1,3-丙二醇的选择性在实际应用中更为重要.表征分析表明,无论对于Pt/WOx还是Pt/WOx/Al2O3催化剂,大部分的La都在Pt颗粒上;同时La的引入提高了催化剂的酸量.在贵金属助剂中,Ru,Ir改性的Pt/WOx和Pt/WOx/Al2O3催化剂上,1,3-丙二醇的收率均有所降低,Ru助剂的降低幅度较小.相反,助剂Rh对Pt/WOx和Pt/WOx/Al2O3催化剂上反应性能的影响截然不同:Rh/Pt/WOx催化剂上1,3-丙二醇的收率从13.1%降到8.7%,Rh/Pt/WOx/Al2O3的1,3-丙二醇收率从31.5%略升到32.4%.另外,由于前期研究表明助剂铝的担载顺序对催化活性有重要影响,因此我们对铂、钨、铝的担载顺序进行了考察.研究表明,在活性组分铂上担载铝或钨物种对催化活性有一定程度的抑制;催化剂体系中钨的含量直接影响甘油的转化率和产物的选择性;含量过少时,甘油转化率极低并以1,2-丙二醇为主要产物.虽然大部分助剂对铂-钨催化剂体系没有明显的促进作用,但是助剂的添加通常可以抑制活性组分的烧结、提高催化剂的稳定性;因此,我们筛选出的La,Fe,Re,Ru,Rh等助剂仍具有深入研究的价值和工业应用的潜力.

关键词: 甘油, 氢解, 1,3-丙二醇, 氧化钨, 助剂

Abstract:

Diverse promoters, including noble metals(such as Ru, Ir and Rh) and transition metal oxides(such as Re, La, Fe, Zr, Sn and Ce oxides) were introduced into Pt/WOx and Pt/WOx/Al2O3 catalysts to investigate the ability of these promoters to modify activity and selectivity during glycerol hydrogenolysis to 1,3-propanediol. Among these, La exhibited the greatest promotional effect; the introduction of 0.1% La to the Pt/WOx improved activity, selectivity and stability, although the significant increase in selectivity came at the cost of a slight activity loss in the case of the Pt/WOx/Al2O3 catalyst. Transmission electron microscopy, high angle annular dark field scanning tunneling electron microscopy and NH3-temperature programmed desorption all demonstrated that the introduction of La generates a greater quantity of acidic sites on the catalyst surface, and that the majority of the La species are associated with Pt particles. Most of the other additives resulted in only minimal improvements or even detrimental effects with regard to both activity and selectivity, although some appear to improve the stability of the catalyst.

Key words: Glycerol, Hydrogenolysis, 1,3-propanediol, Tungsten oxide, Promoter