高活性Cu-ZnO@SiO2纳米催化剂催化CO2加氢制甲醇

doi:10.7503/cjcu20230268

高等学校化学学报 ›› 2023, Vol. 44 ›› Issue (11): 20230268.doi: 10.7503/cjcu20230268

高活性Cu-ZnO@SiO₂纳米催化剂催化CO₂加氢制甲醇

陈浩¹, 陈桂², 宋丹丹¹, 曾艳红¹, 刘文虎³(), 张明⁴()

^1.岳阳职业技术学院生物环境工程学院, 岳阳 414000
^2.怀化学院化学与材料工程学院, 怀化 418000
^3.湖南石油化工职业技术学院石化工程学院, 4. 机电工程学院, 岳阳 414000

收稿日期:2023-06-05 出版日期:2023-11-10 发布日期:2023-08-04
通讯作者: 刘文虎 E-mail:liuwenhu2023@163.com;ming84122023@163.com
作者简介:张明, 男, 学士, 讲师, 主要从事C1资源转化方面的研究. E-mail: ming84122023@163.com
基金资助:
湖南省自然科学基金(2023JJ50309)

High-performance Cu-ZnO@SiO₂ Nano-catalyst for CO₂ Hydrogenation to Methanol

CHEN Hao¹, CHEN Gui², SONG Dandan¹, ZENG Yanhong¹, LIU Wenhu³(), ZHANG Ming⁴()

^1.College of Bioligical and Environmental Engineering，Yueyang Vocational and Technical College，Yueyang 414000，China
^2.College of Chemistry and Materials Engineering，Huaihua University，Huaihua 418000，China
^3.College of Petrochemical Engineering
^4.College of Mechanical and Electrical Engineering，Hunan Petrochemical Vocational Technology College，Yueyang 414000，China

Received:2023-06-05 Online:2023-11-10 Published:2023-08-04
Contact: LIU Wenhu E-mail:liuwenhu2023@163.com;ming84122023@163.com
Supported by:
the Natural Science Foundation of Hunan Province, China(2023JJ50309)

摘要/Abstract

摘要：

铜基催化剂可被广泛应用于CO₂加氢制甲醇, 其催化活性高度依赖载体. 本文通过Stöber法合成了SiO₂纳米微球, 将其作为载体制备了Cu-ZnO@SiO₂催化剂；将该催化剂应用于CO₂加氢制甲醇, 并与常规共沉淀法制备的Cu-ZnO催化剂进行了对比. 通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、 X射线光电子能谱（XPS）、氢气程序升温还原（H₂-TPR）和二氧化碳程序升温脱附（CO₂-TPD）等手段对催化剂进行了表征. 结果表明， Cu-ZnO@SiO₂催化剂具有更高的Cu分散性和CO₂吸附能力, SiO₂的加入提高了催化剂表面Cu⁺/Cu⁰的比例, 从而影响了催化性能. 研究发现, 在H₂/CO₂摩尔比为3, 230 ℃, 2.0 MPa和气体体积空速为3600 mL·g $c a t - 1$ ·h^-1条件下, Cu-ZnO@SiO₂催化剂具有更高的催化活性（甲醇选择性88.2%, 甲醇收率11.1%）, 远高于Cu-ZnO催化剂（甲醇选择性36.5%, 甲醇收率6.9%）. 原位红外光谱（DRIFT）分析表明， CO₂在Cu-ZnO@SiO₂催化剂上主要通过RWGS+CO加氢路径生成甲醇.

关键词: 催化剂, 二氧化碳加氢, 甲醇

Abstract:

Cu-based catalysts are widely employed for CO₂ hydrogenation to methanol. However， their catalytic performance highly depends on supports. Herein， the nano-spherical SiO₂ support was synthesized by the Stöber method and used as a component in Cu-ZnO@SiO₂ catalyst. The catalyst was tested in hydrogenation of CO₂ to methanol and compared with the Cu-ZnO catalyst（6.9% yield of methanol and 36.5% selectivity of methanol） prepared via conventional coprecipitation process. It was found that Cu-ZnO@SiO₂ catalyst exhibits the best catalytic performance， the yield of methanol reached 11.1% with 88.2% selectivity of methanol at n（H₂）/n（CO₂）=3，230 ℃， 2.0 MPa and gaseous hourly space velocity（GHSV）=3600 mL·g $c a t - 1$ ·h^-1. The catalysts were thoroughly characterized by X-ray diffraction（XRD）， scanning electron microscope（SEM）， X-ray photoelectron spectroscopy（XPS）， tempera-ture-programmed reduction（H₂-TPR） and CO₂ temperature-programmed desorption（CO₂-TPD）. The results show that Cu-ZnO@SiO₂ catalyst has higher Cu dispersion and CO₂ adsorption capacity， and the addition of SiO₂ increases the Cu⁺/Cu⁰ molar ratio on the catalyst surface， which affects the catalytic performance. The characterization analysis of Diffuse reflectance fourier transform infrared spectroscopy（DRIFT） showed that CO₂ generated methanol on Cu-ZnO@SiO₂ catalyst mainly through reverse water gas reaction（RWGS）+CO hydrogenation path.

Key words: Catalyst, CO₂ hydrogenation, Methanol

中图分类号:

O643.36

TrendMD:

陈浩, 陈桂, 宋丹丹, 曾艳红, 刘文虎, 张明. 高活性Cu-ZnO@SiO₂纳米催化剂催化CO₂加氢制甲醇. 高等学校化学学报, 2023, 44(11): 20230268.

CHEN Hao, CHEN Gui, SONG Dandan, ZENG Yanhong, LIU Wenhu, ZHANG Ming. High-performance Cu-ZnO@SiO₂ Nano-catalyst for CO₂ Hydrogenation to Methanol. Chem. J. Chinese Universities, 2023, 44(11): 20230268.

图/表 12

Fig.1 XRD patterns of CuO⁃ZnO and CuO⁃ZnO@SiO2 catalysts

Fig.2 Adsorption⁃desorption isotherms(A) and pore size distributions(B) of the CuO⁃ZnO and CuO⁃ZnO@SiO2 catalysts

Table 1 Textural properties of the CuO-ZnO and CuO-ZnO@SiO2 catalysts

Sample	S_BET/（m²·g^-1）	Pore volume/（cm³·g^-1）	Pore diameter/nm
CuO⁃ZnO	58.5	0.10	25.9
CuO⁃ZnO@SiO₂	80.2	0.13	10.2

Fig.3 SEM images of CuO⁃ZnO(A) and CuO⁃ZnO@SiO2(B) catalysts

Fig.4 TEM images(A, C, E) and particle size distribution histograms(B, D, F) and HRTEM image(G) of the CuO⁃ZnO(A, B) and CuO⁃ZnO@SiO2(C—H) catalysts

Fig.5 H2⁃TPR profiles of the CuO⁃ZnO and CuO⁃ZnO@SiO2 catalysts

Fig.6 CO2⁃TPD profiles of the Cu⁃ZnO and Cu⁃ZnO@SiO2 catalysts

Fig.7 Cu2p (A), Zn2p (B), CuAuger(C) and O1s (D) XPS spectra of Cu⁃ZnO and Cu⁃ZnO@SiO2 catalysts

Fig.8 CO2 conversion, methanol selectivity(A) and methanol yield(B) of the Cu⁃ZnO and Cu⁃ZnO@SiO2 catalystsReaction conditions: H2/CO2 molar fraction: 3; total pressure: 2.0 MPa; GHSV=3600 mL·gcat-1·h-1.

Table 2 Catalytic performance of Cu-based catalyst modified by SiO2 in CO2 hydrogenation to methanol

Catalyst	Conversion of CO₂（%）	Selectivity of CH₃OH（%）	Yield of CH₃OH（%）	Ref.
Cu⁃ZnO/SiO₂	14.1	57.2	8.1	［24］
Cu/SiO₂	5.2	79.3	4.1	［25］
Cu⁃ZnO⁃ZrO₂⁃SiO₂	18.5	36.3	6.7	［13］
Cu⁃ZnO⁃Al₂O₃/SiO₂	20.24	27.15	5.5	［26］
Cu⁃ZnO⁃ZrO₂⁃SiO₂	13	38.5	5	［15］
Cu@m⁃SiO₂	10.2	26.5	2.7	［27］
Cu/ZnO@m⁃SiO₂	11.9	61.8	7.4	［27］
CuIn@SiO₂	12.5	78.2	9.8	［28］
Cu⁃ZnO@SiO₂	12.6	88.2	11.1	This work

Fig.9 In situ DRIFT spectra of CO2 hydrogenation over Cu⁃ZnO(A, C) and Cu⁃ZnO@SiO2(B, D) with the scanning range of 800—2200 cm-1(A, B) and 2500—4000 cm-1(C, D) under 0.1 MPa and 230 ℃

Table 3 IR peak assignments of intermediate species over catalyst surface in CO2 hydrogenation

Surface species

ν ˜

/cm^-1

Assignment

Bidentate formate（bi⁃HCOO^*）

1352

1571

2938

2989

ν_s（O—C—O）

ν_as（O—C—O）

ν（CH）

δ（CH）+ν_s（OCO）

Methoxy（CH₃O^*）

1102

2823

2927

ν（O—C）

ν_s（CH₃）

ν_as（CH₃）

CO^*

2084

ν（C=O）