Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride

Vanadium phosphate catalysts are well known as the active phase and are commercially used for the selective oxidation of n-butane to maleic anhydride. They represent the sole example of a commercialized material for the catalytic oxidation of an alkane. In this study, vanadium phosphate catalysts we...

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Main Author:	Rownaghi, Ali Asghar
Format:	Thesis
Language:	English English
Published:	2007
Subjects:	Vanadium catalysts. Maleic anhydride. Oxidation.
Online Access:	http://psasir.upm.edu.my/id/eprint/5085/1/FS_2007_58.pdf
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spelling	my-upm-ir.50852013-05-27T07:20:18Z Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride 2007 Rownaghi, Ali Asghar Vanadium phosphate catalysts are well known as the active phase and are commercially used for the selective oxidation of n-butane to maleic anhydride. They represent the sole example of a commercialized material for the catalytic oxidation of an alkane. In this study, vanadium phosphate catalysts were synthesised via three methods including two new methods i.e. new organic and solvothermal method and via dihydrate method. These catalysts were modified by microwave irradiation, addition of dopants and reducing agent. The effect of reducing agents (i.e. isobutyl alcohol, 1-butanol and ethylene glycol), distilled water, microwave irradiation and conventional heating were investigated. Both heating methods gave similar XRD patterns, however microwave irradiated sample showed higher crystallinity which indicated by the high intensity of the peaks. The microwave treated catalysts exhibit a more homogeneous distribution of the rosette- shape surface species and thin structure which consequently enhanced the specific surface area. However, microwave irradiation and the used of water treatment to enhance the crystalline phase, morphology and also increased the total amount of the oxygen species removed. The introduction of Nb, La and Ce as dopants to (VO)2P2O7 catalysts prepared via reduction of VOPO4·2H2O gives significantly increased the surface area and subsequently improved the conversion efficiency of the catalyst. A new organic route for preparation of high surface area (>50 m2g-1) of vanadium phosphate catalyst was developed, by reducing the time from 26 to only 8 h. This together with incorporation of dopants such as Nb, La, and Ce can increase the surface area by reducing the particle size to nanoparticle. The high surface area contributed to higher mobility and better activity of the lattice oxygen and enhanced the conversion and selectivity for achieve a significant yield of maleic anhydride. The new organic route also increased the amount of V5+ phase in the catalyst. An appropriate amount of V5+ phase presence significantly enhanced the activity of VPO catalysts. A novel solvothermal method was also developed by using a number of primary alcohols (C3-C10) at various temperatures (<423 K, 72 h) via a mild solvothermal synthesis to prepare phase-pure crystalline (VO)2P2O7 with specific surface area up to three fold higher than that can be achieved by hydrothermal method. Furthermore, (VO)2P2O7 solid solution can be crystallized in alcohols at temperature lower than that required by hydrothermal conversion. The intensity of (020) phase of nanocrystalline VPO catalyst prepared by the solvothermal were remarkably higher than the hydrothermal method. Another advantage of this new method for the synthesis of the solid solution of vanadium phosphate catalyst is the low consumption of organic media in a close autoclave system. This eliminates the usage of water and yielded higher n-butane conversion catalyst as compared to conventional organic VPO method. Vanadium catalysts. Maleic anhydride. Oxidation. 2007 Thesis http://psasir.upm.edu.my/id/eprint/5085/ http://psasir.upm.edu.my/id/eprint/5085/1/FS_2007_58.pdf application/pdf en public phd doctoral Universiti Putra Malaysia Vanadium catalysts. Maleic anhydride. Oxidation. Science English
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English English
topic	Vanadium catalysts. Maleic anhydride. Oxidation.
spellingShingle	Vanadium catalysts. Maleic anhydride. Oxidation. Rownaghi, Ali Asghar Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride
description	Vanadium phosphate catalysts are well known as the active phase and are commercially used for the selective oxidation of n-butane to maleic anhydride. They represent the sole example of a commercialized material for the catalytic oxidation of an alkane. In this study, vanadium phosphate catalysts were synthesised via three methods including two new methods i.e. new organic and solvothermal method and via dihydrate method. These catalysts were modified by microwave irradiation, addition of dopants and reducing agent. The effect of reducing agents (i.e. isobutyl alcohol, 1-butanol and ethylene glycol), distilled water, microwave irradiation and conventional heating were investigated. Both heating methods gave similar XRD patterns, however microwave irradiated sample showed higher crystallinity which indicated by the high intensity of the peaks. The microwave treated catalysts exhibit a more homogeneous distribution of the rosette- shape surface species and thin structure which consequently enhanced the specific surface area. However, microwave irradiation and the used of water treatment to enhance the crystalline phase, morphology and also increased the total amount of the oxygen species removed. The introduction of Nb, La and Ce as dopants to (VO)2P2O7 catalysts prepared via reduction of VOPO4·2H2O gives significantly increased the surface area and subsequently improved the conversion efficiency of the catalyst. A new organic route for preparation of high surface area (>50 m2g-1) of vanadium phosphate catalyst was developed, by reducing the time from 26 to only 8 h. This together with incorporation of dopants such as Nb, La, and Ce can increase the surface area by reducing the particle size to nanoparticle. The high surface area contributed to higher mobility and better activity of the lattice oxygen and enhanced the conversion and selectivity for achieve a significant yield of maleic anhydride. The new organic route also increased the amount of V5+ phase in the catalyst. An appropriate amount of V5+ phase presence significantly enhanced the activity of VPO catalysts. A novel solvothermal method was also developed by using a number of primary alcohols (C3-C10) at various temperatures (<423 K, 72 h) via a mild solvothermal synthesis to prepare phase-pure crystalline (VO)2P2O7 with specific surface area up to three fold higher than that can be achieved by hydrothermal method. Furthermore, (VO)2P2O7 solid solution can be crystallized in alcohols at temperature lower than that required by hydrothermal conversion. The intensity of (020) phase of nanocrystalline VPO catalyst prepared by the solvothermal were remarkably higher than the hydrothermal method. Another advantage of this new method for the synthesis of the solid solution of vanadium phosphate catalyst is the low consumption of organic media in a close autoclave system. This eliminates the usage of water and yielded higher n-butane conversion catalyst as compared to conventional organic VPO method.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Rownaghi, Ali Asghar
author_facet	Rownaghi, Ali Asghar
author_sort	Rownaghi, Ali Asghar
title	Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride
title_short	Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride
title_full	Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride
title_fullStr	Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride
title_full_unstemmed	Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride
title_sort	development of new methods for synthesizing reactive nanostructured vanadium phosphate catalysts for partial oxidation of n-butane to maleic anhydride
granting_institution	Universiti Putra Malaysia
granting_department	Science
publishDate	2007
url	http://psasir.upm.edu.my/id/eprint/5085/1/FS_2007_58.pdf
_version_	1747810347862982656

Development of New Methods for Synthesizing Reactive Nanostructured Vanadium Phosphate Catalysts for Partial Oxidation of N-Butane to Maleic Anhydride

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