CePO4 （in particular, monoclinic CePO4） has been rarely used to make supported catalysts. Herein, monoclinic CeP04 nanoparticles were prepared by calcining hexagonal CePO4 nanomds （prepared by precipitation） in ai...CePO4 （in particular, monoclinic CePO4） has been rarely used to make supported catalysts. Herein, monoclinic CeP04 nanoparticles were prepared by calcining hexagonal CePO4 nanomds （prepared by precipitation） in air at 900 ℃. Monoclinic CePO4 nanowires were prepared by calcining hexagonal CePO4 nanowires （prepared by hydrothermal synthesis at 150 ℃） in air at 900 ℃. Both monoclinic CePO4 materials were used to support Rh2O3 by impregnation using Rh（NO3）3 as a precursor （followed by calcination）. The catalytic performance of Rh2O3/monoclinic CePO4 composite materials in N2O decomposition and CO oxidation was investigated. It was found that Rh2O3 supported on monoclinic CePO4 nanowims was much more active than Rh2O3 supported on monoclinic CePO4 nanoparticles. The stability of catalysts as a function of reaction time on stream was studied in both reactions. The influence of co-fed CO2, O2, and H2O on the catalytic activity in N20 decomposition was also studied. These catalysts were characterized by employing N2 adsorption-desorption, ICP-OES, XRD, TEM, XPS, H2-TPR, O2-TPD, and CO2-TPD. The correlation between physicochemical properties and catalytic properties was discussed.展开更多
Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5 （Si/Al ratio = 15） with aqueous solutions of differ- ent Cu precursors （CuCl2, Cu（NO3）2, CuSO4, Cu（CH3COO）2, and ammoniacal copper （II） complex ion）...Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5 （Si/Al ratio = 15） with aqueous solutions of differ- ent Cu precursors （CuCl2, Cu（NO3）2, CuSO4, Cu（CH3COO）2, and ammoniacal copper （II） complex ion）. After being pretreated in flowing He at 500 ℃ to form active Cu＋, these catalysts exhibited quite different activities in cata- lytic decomposition of N2O. CZM-AC（II） （prepared by ammoniacal copper （II） complex ion） with 9.4 wt% Cu con- tent was the most active among these Cu-ZSM-5 catalysts, achieving almost complete N2I conversion at 400 ℃. CZM-CA （prepared using Cu（ CH3COO）2 as the Cu precursor） with 2.8 wt% Cu content was the second most active catalyst among these Cu-ZSM-5 catalysts, achieving almost complete N2I conversion at 425 ℃. CZM-CC, CZM- CN, and CZM-CS prepared by using CuCl2, Cu（NO3）2, or CuSO4 as the Cu precursor with similar Cu contents （≈1.7 wt%） were the least active among these Cu-ZSM-5 catalysts, achieving ca. 90% N2O conversion at 500 ℃. XRD, ICP, SEM, TEM, EDX-mapping, and CO-IR experiments were conducted to characterize relevant samples. The superior activity of CZM-AC（II） can be attributed to the high contents of total Cu＋ and dimeric Cu＋ among these samples. The influence of co-fed O2 or H2O on the catalytic performance of typical samples was also studied.展开更多
Single-atom catalysts(SACs)have attracted extensive attention in the field of heterogeneous catalysis.However,the fabrication of SACs with high loading and hightemperature stability remains a grand challenge,especiall...Single-atom catalysts(SACs)have attracted extensive attention in the field of heterogeneous catalysis.However,the fabrication of SACs with high loading and hightemperature stability remains a grand challenge,especially on oxide supports.In this work,we have demonstrated that through strong covalent metal-support interaction,highloading and thermally stable single-atom Pt catalysts can be readily prepared by using Fe modified spinel as support.Better catalytic performance in N2O decomposition reaction is obtained on such SACs than their nanocatalyst counterpart and low-surface-area Fe2O3 supported Pt SACs.This work provides a strategy for the fabrication of high-loading and thermally stable SACs for applications at high temperatures.展开更多
Nd-Co 3O 4 catalysts were prepared by hydrothermal and co-precipitation methods to catalyze the decomposition of N 2O. The catalysts prepared by hydrothermal method showed higher activity. Among the hydrothermal Nd-Co...Nd-Co 3O 4 catalysts were prepared by hydrothermal and co-precipitation methods to catalyze the decomposition of N 2O. The catalysts prepared by hydrothermal method showed higher activity. Among the hydrothermal Nd-Co 3O 4 catalysts, the catalyst with Nd/Co molar ratio of 0.01 had higher activity. 0.01Nd-Co 3O 4 catalyst was then impregnated by K 2CO 3 solution to prepare K-modified catalyst. The catalysts were characterized by means of X-ray diffraction (XRD), nitrogen physisorption, scanning electrons microscopy (SEM), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H 2-TPR), and oxygen temperature-programmed desorption (O 2-TPD). The results show that Nd-Co 3O 4 and K-modified catalysts exhibit spinel structure. In contrast to bare Nd-Co 3O 4, the K-modified catalyst with higher activity is due to its weaker strength of Co-O bond and easier desorption of surface oxygen species. In addition, over 90% conversion of N 2O can be reached over 0.02K/0.01Nd-Co 3O 4 at 350 ℃ for 40 h under the co-presence of oxygen and steam in feed gases.展开更多
基金Supported by the National Natural Science Foundation of China(21177028,21477022)
文摘CePO4 （in particular, monoclinic CePO4） has been rarely used to make supported catalysts. Herein, monoclinic CeP04 nanoparticles were prepared by calcining hexagonal CePO4 nanomds （prepared by precipitation） in air at 900 ℃. Monoclinic CePO4 nanowires were prepared by calcining hexagonal CePO4 nanowires （prepared by hydrothermal synthesis at 150 ℃） in air at 900 ℃. Both monoclinic CePO4 materials were used to support Rh2O3 by impregnation using Rh（NO3）3 as a precursor （followed by calcination）. The catalytic performance of Rh2O3/monoclinic CePO4 composite materials in N2O decomposition and CO oxidation was investigated. It was found that Rh2O3 supported on monoclinic CePO4 nanowims was much more active than Rh2O3 supported on monoclinic CePO4 nanoparticles. The stability of catalysts as a function of reaction time on stream was studied in both reactions. The influence of co-fed CO2, O2, and H2O on the catalytic activity in N20 decomposition was also studied. These catalysts were characterized by employing N2 adsorption-desorption, ICP-OES, XRD, TEM, XPS, H2-TPR, O2-TPD, and CO2-TPD. The correlation between physicochemical properties and catalytic properties was discussed.
基金Supported by the National Natural Science Foundation of China(Grant No.21477022)
文摘Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5 （Si/Al ratio = 15） with aqueous solutions of differ- ent Cu precursors （CuCl2, Cu（NO3）2, CuSO4, Cu（CH3COO）2, and ammoniacal copper （II） complex ion）. After being pretreated in flowing He at 500 ℃ to form active Cu＋, these catalysts exhibited quite different activities in cata- lytic decomposition of N2O. CZM-AC（II） （prepared by ammoniacal copper （II） complex ion） with 9.4 wt% Cu con- tent was the most active among these Cu-ZSM-5 catalysts, achieving almost complete N2I conversion at 400 ℃. CZM-CA （prepared using Cu（ CH3COO）2 as the Cu precursor） with 2.8 wt% Cu content was the second most active catalyst among these Cu-ZSM-5 catalysts, achieving almost complete N2I conversion at 425 ℃. CZM-CC, CZM- CN, and CZM-CS prepared by using CuCl2, Cu（NO3）2, or CuSO4 as the Cu precursor with similar Cu contents （≈1.7 wt%） were the least active among these Cu-ZSM-5 catalysts, achieving ca. 90% N2O conversion at 500 ℃. XRD, ICP, SEM, TEM, EDX-mapping, and CO-IR experiments were conducted to characterize relevant samples. The superior activity of CZM-AC（II） can be attributed to the high contents of total Cu＋ and dimeric Cu＋ among these samples. The influence of co-fed O2 or H2O on the catalytic performance of typical samples was also studied.
基金supported by the National Key Projects for Fundamental Research and Development of China(2016YFA0202801)the National Natural Science Foundation of China(21673226+3 种基金91645203 and 21590792)the “Transformational Technologies for Clean Energy and Demonstration”the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA21040200 and XDB17000000)supported by the Tsinghua Xuetang Talents Program
文摘Single-atom catalysts(SACs)have attracted extensive attention in the field of heterogeneous catalysis.However,the fabrication of SACs with high loading and hightemperature stability remains a grand challenge,especially on oxide supports.In this work,we have demonstrated that through strong covalent metal-support interaction,highloading and thermally stable single-atom Pt catalysts can be readily prepared by using Fe modified spinel as support.Better catalytic performance in N2O decomposition reaction is obtained on such SACs than their nanocatalyst counterpart and low-surface-area Fe2O3 supported Pt SACs.This work provides a strategy for the fabrication of high-loading and thermally stable SACs for applications at high temperatures.
基金The project was supported by the Shandong Natural Science Foundation (ZR2017MB020)Graduate Innovation Foundation of Yantai University (YDYB1909).
文摘Nd-Co 3O 4 catalysts were prepared by hydrothermal and co-precipitation methods to catalyze the decomposition of N 2O. The catalysts prepared by hydrothermal method showed higher activity. Among the hydrothermal Nd-Co 3O 4 catalysts, the catalyst with Nd/Co molar ratio of 0.01 had higher activity. 0.01Nd-Co 3O 4 catalyst was then impregnated by K 2CO 3 solution to prepare K-modified catalyst. The catalysts were characterized by means of X-ray diffraction (XRD), nitrogen physisorption, scanning electrons microscopy (SEM), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H 2-TPR), and oxygen temperature-programmed desorption (O 2-TPD). The results show that Nd-Co 3O 4 and K-modified catalysts exhibit spinel structure. In contrast to bare Nd-Co 3O 4, the K-modified catalyst with higher activity is due to its weaker strength of Co-O bond and easier desorption of surface oxygen species. In addition, over 90% conversion of N 2O can be reached over 0.02K/0.01Nd-Co 3O 4 at 350 ℃ for 40 h under the co-presence of oxygen and steam in feed gases.
