Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases p. 3173 - 3186 (1989)
Update date:2022-08-11
Topics:
Petrakis, Dimitris E.
Pomonis, Philip J.
Sdoukos, Antonios T.
Phosphate salts of the metals Al, Fe and Cr supported on alumina were prepared by co-precipitation with NH3 from solutions containing calculated amounts of the metal nitrates and phosphoric acid.The atomic ratio of the elements participating in the solids was Al:P:M = 100:x:20 where M = Al, Fe, Cr and x = 0, 4.5, 9, 18, 36, 72 and 144.The parent compounds Al100PxAl20 are formed by an endothermic decomposition of NH4NO3, which exist in the dried precipitant, to NH3 and HNO3.The resulting solids for x = 0 contain just γ-Al2O3, for x = 144 AlPO4 plus an amorphous phase, while for intermediate values of x a totally amorphous phase is formed.Substitution of 20 percent Al by Fe alters slightly the route of decomposition, the endo-effect noticed above is followed by a small exothermic one, meaning probably the decomposition of part of the resulting nitric acid through anion breakdown to N2, H2O and O2.The structure of the resulting solids corresponds to α-M2O3 for x = 0 and MPO4 for x = 144, while for intermediate values amorphous materials are formed.An addition of Cr instead of Fe alters completely the route of decomposition of NH4NO3 to N2, H2O and O2 for reasons similar to those noticed for Fe.For x = 0 the resulting solids contain α-M2O3 oxides alone, for x = 144 they are totally amorphous and for intermediate values of x an amorphous phase plus crystalline Cr2O3 is formed.The behaviour of these systems for a simple redox reaction, namely N2O decomposition, shows a continuous drop of activity with phosphorous content.An analysis of the results according to the kinetic theory of poisoning indicates an order of deactivation between one and two, depending on the catalyst and the temperature.A mechanism which may explain this result is proposed.Thiele modulus and effectiveness factors which have been calculated show that for AlPAl and AlPCr species internal diffusion is the rate-determining step and the reaction occurs mainly on the external surface.For the AlPFe catalysts the rate of diffusion is almost equal to that of reaction.
Contact:+86 755 26588093
Address:No.9 Linkong West Street, Hengdian Street, Huangpi District, Wuhan City, China.
website:http://www.cheminn.com/
Contact:86-531-67875205
Address:No.9-2,South of Shanda Road, Jinan ,China
Jinan Jianfeng Chemical Co., Ltd
Contact:0086-531-88110457
Address:sales01(-a-t-)pharmachemm{dot}c+o+m
Beijing Tianjia Chemical Science & Technology Co.,Ltd
Contact:86-0550-2392698
Address:No.388, Shiliang Road (East),
Nanjing Capatue Chemical Co., Ltd
Contact:+86-25-86371192 +86-025-85720158
Address:No.20 Jiangjun Avenue, Jiangning Economic & Technical Development Zone
Doi:10.1016/j.jfluchem.2014.05.013
(2014)Doi:10.1002/(SICI)1099-1344(199707)39:7<601::AID-JLCR2>3.0.CO;2-V
(1997)Doi:10.1021/acs.cgd.6b01011
(2016)Doi:10.1021/jacs.5b08045
(2015)Doi:10.1021/jf5033284
(2014)Doi:10.1016/j.tetlet.2007.08.094
(2007)
