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Synthesis And Catalytic Properties Of Mesoporous Nickel Phosophate Materials

Posted on:2011-05-05Degree:MasterType:Thesis
Country:ChinaCandidate:M LiFull Text:PDF
GTID:2121360305455751Subject:Industrial Catalysis
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In this paper, mesoporous nickel phosphate materials have been synthesized by using cetyltrimethylammonium bromide (CTABr), cetyltrimethylammonium chloride (CTACl) and Dodecyltrimethylammonium Chloride (DTACl) as the templates, named NiPO-Br, NiPO-Cl and NiPO-D. Physical and chemical Properties of the materials were studied with XRD, TEM and FT-IR etc. Meanwhile, we also systematically studied the influences of the surfactants' anion and carbon chain length on synthesis of the mesoporous nickel phosophate materials.The experimental results showed that nano tubular mesoporous nickel phosphate materials can be synthesized with CTABr, CTACl and DTACl as the templates; anion of the surfactants had little effect on synthesis of the materials, while carbon chain length had great relationship with structure of the materials. All the materials didn't belong to hexagonal phase apace with the results of XRD and TEM.The pH of the mother liquor was adjusted by ammonia. The synthesis phase region of two mesoporous nickel phosphate materials were determined with an investigation on pH of the system and the composition of the reaction materials. In order to obtain high purity materials with CTABr as the templates, NH4+/P should be controlled between 2.10~2.38, pH 8~10 while Ni/P 0.5~0.7. Synthesis phase region using CTACl as the templates is that NH4+/P 1.52~2.03, pH of the gel 6-9 and Ni/P 0.65-1.0. In addition, in order to obtain high purity materials with DTACl as the templates, NH4+/P should be controlled between 1.22~1.82, pH 5~9 and Ni/P 0.5~1.0. In this paper, we discussed the synthesis mechanism of tubular mesoporous nickel phosphate materials. We also studied the influences of cationic templates'anion. It is considered that nano tubular nano tubular mesoporous nickel phosphate materials may be synthesized by cationic surfactant self-assembly method, that is the self-assembly between organic templates and inorganic precursor of nickel phosphates.UV-Vis diffuse reflectance spectroscopy of mesoporous nickel phosophate materials show that Ni in the mesoporous nickel phosophate materials had the structure of distortion cathedral. Cationic Ni still had the structure of distortion cathedral after extracted, while Ni had four-coordination in the heat-treated samples. Framework structure of the mesoporous nickel phosophate materials was kept good after extracted with organic solvent. Meanwhile, the templates were removed effectively, and orderliness of the materials was improved.Applying NiPO-Cl materials to HDS and HDN, the consequence showed that selectivity of BP was 20% higher than the catalyst of Ni2P, while catalytic activities was lower than the catalyst of Ni2P.
Keywords/Search Tags:Mesoporous nickel phosophates, Nano-tubes, Cationic surfactants, Synthesis, Application
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