Direct synthesis of furfuryl alcohol from furfural: catalytic performance of monometallic and bimetallic Mo and Ru phosphides
Direct synthesis of furfuryl alcohol from furfural: catalytic performance of monometallic and bimetallic Mo and Ru phosphides
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DOI：
10.1039/c9cy00705a
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发表时间：
2019-07-21
影响因子：
5
通讯作者：
Hicks, Jason C.
中科院分区：
文献类型：
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作者：
Bonita, Yolanda;Jain, Varsha;Hicks, Jason C.
考察了磷化钌、磷化钼对糠醛选择性加氢合成糠醇的催化性能。MonclerMoP显示出对糠醇的高选择性（98%），而RuP和Ru 2 P在相当的转化率下显示出较低的选择性。用Ru1.0Mo1.0P观察到双金属促进效应，因为糠醛氢化成糠醇的伪一级反应速率常数k（1）比MoP、RuP和Ru 2 P高至少5倍，同时保持99%的选择性。RuxMo 2-xP（0.8 < x < 1.2）的组成导向催化研究提供了富含Ru的组成积极影响k（1）但不影响选择性的证据。与甲基呋喃（k（2））和四氢糠醇（k（3））相比，糠醇生产的速率常数比k（1）/（k（2）+ k（3））遵循Ru1.0Mo1.0P > Ru1.2Mo0.8P > MoP > Ru0.8Mo1.2P > RuP > Ru 2 P的趋势。采用漫反射红外傅里叶变换光谱（DRIFTS）研究了糠醛在合成催化剂上的吸附构型，但结果不确定，且与糠醛的选择性没有相关性，这是由于糠醛的吸附可能存在红外非活性表面模式。然而，气相密度泛函理论计算表明，在RuxMo 2-xP（0.8 < x < 1.2）中x = 1.0的材料具有最有利的糠醛吸附能。在实验中，我们还观察到，溶剂极大地影响转化率和选择性，其中异丙醇提供了最高的选择性为糠醇。最后，再循环实验表明，在没有任何再生的情况下，经过3次循环后，k（1）降低了12%，但活性可以通过再还原步骤完全恢复。
The catalytic properties of monometallic and bimetallic Ru and Mo phosphides were evaluated for their ability to selectively hydrogenate furfural to furfuryl alcohol. Monometallic MoP showed high selectivity (98%) towards furfuryl alcohol, while RuP and Ru2P exhibited lower selectivity at comparable conversion. Bimetallic promotional effects were observed with Ru1.0Mo1.0P, as the pseudo-first order reaction rate constant for furfural hydrogenation to furfuryl alcohol, k(1), was at least 5x higher than MoP, RuP, and Ru2P, while maintaining a 99% selectivity. Composition-directed catalytic studies of RuxMo2-xP (0.8 < x < 1.2) provided evidence that Ru rich compositions positively influence k(1), but not the selectivity. The rate constant ratio k(1)/(k(2) + k(3)) for furfuryl alcohol production compared to methyl furan (k(2)) and tetrahyrofurfuryl alcohol (k(3)) followed the trend of Ru1.0Mo1.0P > Ru1.2Mo0.8P > MoP > Ru0.8Mo1.2P > RuP > Ru2P. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to examine the configuration of adsorbed furfural on the synthesized catalysts, but the results were inconclusive and no correlation could be found with the selectivity due to the possible IR inactive surface modes with furfural adsorption. However, gas phase density functional theory calculations suggested the x = 1.0 material in RuxMo2-xP (0.8 < x < 1.2) had the most favorable furfural adsorption energy. Experimentally, we also observed that the solvent greatly influenced both the conversion and selectivity, where isopropanol provided the highest selectivity to furfuryl alcohol. Finally, recycling experiments showed a 12% decrease in k(1) after 3 cycles without any regeneration, but the activity could be fully recovered through a re-reduction step.