Effect of alumina support crystal structure of Ru-based catalysts on polyethylene hydrogenolysis performance

doi:10.16085/j.issn.1000-6613.2024-0935

Abstract

Abstract:

The production of fuel from polyethylene (PE) by catalytic hydrogen hydrolysis is an important approach to realize green recycle of PE. In this work, the effect of crystal structure of Al₂O₃ on the performance of Ru-based catalyst for PE hydrogenolysis was investigated. Four kinds of Ru/Al₂O₃ catalysts were prepared by impregnation method, and characterized by TEM, H₂-TPR and XPS to reveal the interaction between active metal Ru and Al₂O₃ support. The experimental results of PE hydrolysis showed that the difference in Al₂O₃ crystal structure led to a significant effect on the catalytic performance. Under the same reaction conditions, the total yield of products by Ru/(δ+α)-Al₂O₃ catalyst was less than 10%, and the methane yield was less than 5%, while the total yield for the other three catalysts was all higher than 90%. Among them, Ru/(θ+α)-Al₂O₃ exhibited the highest methane yield and selectivity, with methane yield higher than 90% and methane selectivity over 95%. By adjusting the hydrogen pressure, it was found that the different coverage of *H led to different reaction behaviors. With the combination of H₂-TPD and CO-DRIFTS characterization methods, it was found that the excess adsorption of *H at the active site Ru⁰ of Ru/γ-Al₂O₃ could result in hydrogen poisoning. For Ru/(θ+α)-Al₂O₃, the adsorption of *H at the active site Ru⁰ and the C—C intermediate could reach adsorption equilibrium. On Ru/(δ+α)-Al₂O₃ catalyst, no *H adsorption on the active site Ru⁰ was detected, hence the total product yield for Ru/(δ+α)-Al₂O₃ was below 10%.

Key words: Ru/Al₂O₃ catalyst, hydrogenation, methane, alumina, adsorption

摘要：

废聚乙烯（PE）通过催化氢解制取燃料产品是实现塑料绿色循环的重要途径之一。本文探究了Al₂O₃晶型对负载型Ru基催化剂在PE催化氢解中反应性能的影响。通过浸渍法制备4种不同晶型的Ru/Al₂O₃催化剂，采用TEM、H₂-TPR和XPS对Ru/Al₂O₃催化剂进行表征，以揭示活性金属Ru与Al₂O₃载体之间的相互作用差异。PE氢解实验的结果表明，Al₂O₃晶型的差异对Ru/Al₂O₃催化剂催化氢解性能产生显著影响。在相同条件下进行PE氢解反应时，Ru/(δ+α)-Al₂O₃上产物总产率低于10%，甲烷的产率低于5%；而其他3种催化剂的产物总产率均高于90%，其中Ru/(θ+α)-Al₂O₃的甲烷产率（>90%）和选择性（>95%）最高。调控氢气反应压力，发现不同的*H覆盖率导致Ru/Al₂O₃催化剂上不同的反应行为。采用H₂-TPD和CO-DRIFTS对Ru/Al₂O₃催化剂进行表征，发现Ru/γ-Al₂O₃上活性位点Ru⁰上的*H的过量吸附，导致了氢中毒；在Ru/(θ+α)-Al₂O₃上，活性位点Ru⁰上的*H吸附和C－C长链吸附达到了平衡；在Ru/(δ+α)-Al₂O₃上，由于Ru ⁿ⁺的含量过高，导致*H在金属Ru上的吸附较弱，从而Ru/(δ+α)-Al₂O₃上产物总产率低于10%。

关键词: Ru/Al₂O₃催化剂, 加氢, 甲烷, 氧化铝, 吸附

CLC Number:

TQ426

GAO Jiaojiao, YAN Shiyu, YANG Taishun, XIE Shangzhi, YANG Yanjuan, XU Jing. Effect of alumina support crystal structure of Ru-based catalysts on polyethylene hydrogenolysis performance[J]. Chemical Industry and Engineering Progress, 2025, 44(7): 3917-3927.

高姣姣, 颜诗宇, 杨太顺, 谢尚志, 杨艳娟, 徐晶. 不同晶型Al₂O₃负载Ru催化剂对聚乙烯氢解的影响[J]. 化工进展, 2025, 44(7): 3917-3927.

Figures/Tables 12

References 35

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样品	比表面积^①/m²·g^-1	孔容^①/cm³·g^-1	样品	比表面积^①/m²·g^-1	孔容^①/cm³·g^-1	Ru质量分数^②/%
α-Al₂O₃	158	1.06	Ru/α-Al₂O₃	157	0.74	3.2
(θ+α)-Al₂O₃	62	0.30	Ru/(θ+α)-Al₂O₃	56	0.27	3.3
γ-Al₂O₃	15	0.04	Ru/γ-Al₂O₃	10	0.03	3.2
(δ+α)-Al₂O₃	55	0.32	Ru/(δ+α)-Al₂O₃	50	0.29	3.2

样品	比表面积^①/m²·g^-1	孔容^①/cm³·g^-1	样品	比表面积^①/m²·g^-1	孔容^①/cm³·g^-1	Ru质量分数^②/%
α-Al₂O₃	158	1.06	Ru/α-Al₂O₃	157	0.74	3.2
(θ+α)-Al₂O₃	62	0.30	Ru/(θ+α)-Al₂O₃	56	0.27	3.3
γ-Al₂O₃	15	0.04	Ru/γ-Al₂O₃	10	0.03	3.2
(δ+α)-Al₂O₃	55	0.32	Ru/(δ+α)-Al₂O₃	50	0.29	3.2

样品	产物产率/%
样品	CH₄	C₂~C₆	C₇~C₄₀
(δ+α)-Al₂O₃	0.002	0.151	1.185
(θ+α)-Al₂O₃	0.041	0.248	1.401
α-Al₂O₃	0.022	0.177	0.637
γ-Al₂O₃	0.020	0.143	1.258

样品	产物产率/%
样品	CH₄	C₂~C₆	C₇~C₄₀
(δ+α)-Al₂O₃	0.002	0.151	1.185
(θ+α)-Al₂O₃	0.041	0.248	1.401
α-Al₂O₃	0.022	0.177	0.637
γ-Al₂O₃	0.020	0.143	1.258