TY - JOUR
T1 - The effect of impurities on chemisorption and activity of MgO-supported Rh
AU - Wang, Jialiang
AU - Lercher, Johannes A.
AU - Haller, Gary L.
N1 - Funding Information:
One of us, Jialiang Wang, thanks the Ministry of Education of the PRC for the fellowship, and Mr. D. E. Resasco for many helpful discussions. This work was supportedi n part by NSF Grant CPE-78-13314. Acknowledgmenti s made to the Donors of the Petroleum Research Fund, administeredb y the American Chemical Society, for partial support of this research.
PY - 1984/7
Y1 - 1984/7
N2 - A study has been made of the effect of the activation temperature on the properties of Rh supported on MgO of various purities. Hydrogen chemisorption, ethane hydrogenolysis, and cyclohexane dehydrogenation were used as tests for metal-support interactions. When either a 98 or 99.5% pure MgO was used as support for Rh, we observed, respectively, a 3- or 20-fold decrease in H2 chemisorption capacity and a 3 or 5 order of magnitude suppression in ethane hydrogenolysis activity after a high temperature reduction (773 K) relative to a low temperautre reduction (523 K). The effect was reversible by oxidation at 673 K followed by reduction at low temperature in H2 and was dependent on the loading of Rh when the dispersion of the metal was kept about constant, i.e., the lower the loading, the more profound the effect. However, little effect of reduction temperatures was observed on H2 adsorption or ethane hydrogenolysis when a 99.999% pure MgO was used as support for Rh. The difference may be attributed to the impurities in the support, and in particular, sulfate is suspected to be the precursor of sulfide poisoning which is responsible for the apparent metal-support interaction in the Rh MgO system.
AB - A study has been made of the effect of the activation temperature on the properties of Rh supported on MgO of various purities. Hydrogen chemisorption, ethane hydrogenolysis, and cyclohexane dehydrogenation were used as tests for metal-support interactions. When either a 98 or 99.5% pure MgO was used as support for Rh, we observed, respectively, a 3- or 20-fold decrease in H2 chemisorption capacity and a 3 or 5 order of magnitude suppression in ethane hydrogenolysis activity after a high temperature reduction (773 K) relative to a low temperautre reduction (523 K). The effect was reversible by oxidation at 673 K followed by reduction at low temperature in H2 and was dependent on the loading of Rh when the dispersion of the metal was kept about constant, i.e., the lower the loading, the more profound the effect. However, little effect of reduction temperatures was observed on H2 adsorption or ethane hydrogenolysis when a 99.999% pure MgO was used as support for Rh. The difference may be attributed to the impurities in the support, and in particular, sulfate is suspected to be the precursor of sulfide poisoning which is responsible for the apparent metal-support interaction in the Rh MgO system.
UR - https://www.scopus.com/pages/publications/0006428864
U2 - 10.1016/0021-9517(84)90045-9
DO - 10.1016/0021-9517(84)90045-9
M3 - Article
AN - SCOPUS:0006428864
SN - 0021-9517
VL - 88
SP - 18
EP - 25
JO - Journal of Catalysis
JF - Journal of Catalysis
IS - 1
ER -