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  • 1. Mosca, Alessandra
    et al.
    Hedlund, Jonas
    Webley, Paul
    Monash University, Melbourne, VIC.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rezaei, Fateme
    Structured zeolite NaX coatings on ceramic cordierite monolith supports for PSA applications2010In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 130, no 1-3, p. 38-48Article in journal (Refereed)
    Abstract [en]

    Novel structured adsorbents in the form of thin zeolite films grown on substrates designed for low pressure drop have a great potential to improve pressure swing adsorption (PSA) processes. In the present work, template free films of NaX zeolite were grown on the walls of ceramic cordierite supports using a seeding technique. The supports had 400 parallel channels per square inch. Films were grown both from a gel and a clear synthesis solution. The materials were analyzed by scanning electron microscopy, X-ray diffraction, N2 adsorption/desorption measurements, Hg-porosimetry as well as CO2 breakthrough experiments. When a gel was used for film growth, a film consisting of well intergrown crystals with a thickness of about 1 μm was obtained. However, a large amount of sediments were deposited on top of the film, which resulted in a dispersed CO2 adsorption breakthrough front. Zeolite films grown in one longer hydrothermal treatment in a clear solution were less intergrown and consisted of both NaX and hydroxysodalite crystals and, in addition, some sediments were deposited on top of the film, which again resulted in a dispersed breakthrough front. By using a multiple-step synthesis procedure and a clear synthesis solution, well intergrown NaX films, free from sediments and with only a very small fraction of hydroxysodalite crystals could be prepared. The CO2 breakthrough front for the latter adsorbent was sharper than the front for an empty adsorption column and only shifted in time. This indicates that the flow distribution in the adsorbent is even and that the mass transfer resistance in the film is very low due to the small film thickness and high effective diffusivity for CO2 in the NaX film and still, the adsorption capacity is considerable. The even flow distribution, very low mass transfer resistance and low pressure drop in combination with considerable adsorption capacity in this adsorbent indicates that it is a promising adsorbent for PSA applications. The findings from the present work will be important for the development of structured adsorbents to use as a competitive alternative to traditionally used adsorbents in PSA.

  • 2. Rezaei, Fateme
    Activity: Thermal management of structured adsorbents in gas separation processes2009Conference paper (Other (popular science, discussion, etc.))
  • 3.
    Rezaei, Fateme
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Optimization of structured adsorbents for gas separation processes2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Conventional gas separation processes using packed beds of beads or granules suffer from high pressure drop and mass transfer resistance when higher throughputs are required, leading to lower productivity and recovery and higher power consumption. This restricts their application to low throughputs and makes them less attractive compared to other processes for large volume production and high productivity. Such problems could be reduced if structured adsorbents are developed and replace the traditional beds of beads or granules. Although much research has been devoted to the development of structured adsorbents over the last decade, there is still a need to increase the understanding of structured adsorbents. Therefore, this work aimed to increase the fundamental understanding of structured adsorbents using two different approaches; a general approach by which numerical models were developed to predict the performance of structured adsorbents with different geometries in pressure/vacuum swing adsorption (PSA/VSA) processes. The effects of parameters such as porosity, density and surface area, on performance of structured adsorbents with different geometries were evaluated. Comparisons based on mass and heat transfer, adsorbent loading and pressure drop characteristics of PSA systems for CO2/N2 separation were carried out. The obtained results demonstrate the potential advantage of structured adsorbents in rapid cycle adsorption processes. The even flow distribution, very low mass and heat transfer resistances and low pressure drop in combination with considerable adsorption capacity in the best structured adsorbents indicate that these novel configurations are promising adsorbents for PSA/VSA applications. The second approach was to evaluate the performance of zeolite coated monoliths prepared and tested experimentally by numerical modelling. The effects of wall porosity, channel width distribution and zeolite film thickness on the dynamic behavior of the adsorbents were examined. The model indicated that the film thickness could be increased up to about 10 µm to increase adsorption capacity without increasing the dispersion in the system further. In addition, it was shown that employment of monoliths with lower wall porosity would lead to better performance of the structured adsorbents.

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  • 4.
    Rezaei, Fateme
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Thermal management of structured adsorbents in CO2 capture processes2012In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 51, no 10, p. 4025-4034Article in journal (Refereed)
    Abstract [en]

    In order to have an efficient adsorptive separation, structured adsorbents are expected to satisfy not only mass transfer and pressure drop requirements but also thermal management requirements. To what extent the structure of adsorbent affects the thermal behavior of the system is a question which will be addressed in this study. The primary purpose of this study was to assess the performance of alternate adsorbents through development of numerical models for prediction of their thermal behavior under a two-step pressure swing adsorption (PSA) condition. The single-step CO 2 breakthrough and temperature profiles confirmed the efficiency of structured adsorbents in managing the thermal effects evolved in the bed under nonisothermal conditions. Two-step PSA results also showed that under real cyclic processes, and especially during rapid cycling, structured adsorbents maintain their superiority and introduce themselves as potential candidates for advanced PSA units. However, the performance of a structured adsorbent is highly dependent on its dimensions and geometrical parameters describing the structures, and these parameters should be optimized for each separation

  • 5.
    Rezaei, Fateme
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Webley, Paul
    Monash University, Melbourne, VIC.
    Engineered gas adsorbents, optimum structure and performance2010Conference paper (Refereed)
  • 6.
    Rezaei, Fateme
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mosca, Alessandra
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Webley, P.A.
    Monash University, Melbourne, VIC.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    The effect of wall porosity and zeolite film thickness on the dynamic behavior of adsorbents in the form of coated monoliths2011In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 81, no 2, p. 191-199Article in journal (Refereed)
    Abstract [en]

    The effects of wall porosity, channel width distribution and zeolite film thickness on the performance of 400 and 1200 cells per square inch (cpsi) cordierite monoliths coated with zeolite X films with thicknesses of 1.5 and 2.5 μm were examined. To investigate the effect of wall porosity and restrict growth of zeolite to the external surface of the monolith channels, the macro pores in the walls of the 1200 cpsi cordierite monoliths were filled with colloidal α-alumina particles. The adsorbents were characterized by Scanning Electron Microscopy, Mercury Intrusion Porosimetry and carbon dioxide breakthrough experiments and a mathematical model describing the diffusion and adsorption in the system was fitted to the data. The model accounted for carbon dioxide uptake by filling the pores in the support by carbon dioxide gas and adsorption of carbon dioxide on cordierite, alumina and zeolite. The model indicates that the uptake of carbon dioxide by adsorption on cordierite is much slower than by pore filling and too slow to influence the very fast breakthrough experiments with monoliths without zeolite film that are over in less than 1 minute. It was shown that the pores in the cordierite monolith result in dispersion by pore filling with carbon dioxide gas, not adsorption. The CO2 adsorption capacity of a 1200 cpsi monolith coated with a 2.5 μm film was 0.13 mmol/cm3 adsorbent, which should be compared to the adsorption capacity of zeolite X beads, which is about 2.3 mmol/cm3 adsorbent. To increase adsorption capacity of a non-porous zeolite coated monolith, film thickness could be increased. The model indicated that the film thickness could be increased up to about 10 μm without increasing the dispersion and thereby approach the adsorption capacity for beads. However, simulation of the whole cycle must be performed in order to find the optimum film thickness for a real cyclic process. This work has lead to better understanding of the role of the support porosity and pore size distribution and film thickness for coated monolith adsorbents.

  • 7. Rezaei, Fateme
    et al.
    Mosca, Alessandra
    Webley, Paul
    Department of Chemical Engineering, Monash University.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Xiao, Penny
    Department of Chemical Engineering, Monash University.
    Comparison of traditional and structured adsorbents for CO2 separation by vacuum swing adsorption2010In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 49, no 10, p. 4832-4841Article in journal (Refereed)
    Abstract [en]

    The development of structured adsorbents with attractive characteristics is an important step in the improvement of adsorption-based gas-separation processes. The improved features of structured adsorbents include lower energy consumption, higher throughput, and superior recovery and purity of product because of the even flow distribution, very low mass-transfer resistance, and low pressure drop in combination with a reasonable adsorption capacity. This study examines the vacuum-swing adsorption (VSA) CO2 separation performance of structured adsorbents in the form of thin NaX films grown on the walls of ceramic cordierite monoliths, and the results are compared with NaX pellets. Adsorption equilibrium and dynamic properties are explored experimentally. The CO2 breakthrough front for the NaX film grown on the 400 cells/in.2 (cpsi) monolith was close to ideal and indicated that axial dispersion was very small and that the mass-transfer resistance in the film was very low. The breakthrough front for the structured adsorbent with 400 cpsi was sharper than that for the structured adsorbent with 900 cpsi and only shifted to shorter breakthrough times because of the lower amount of zeolite and higher effective diffusivity of the former sample. In addition, the CO2 breakthrough fronts for the 400 and 900 cpsi structured adsorbents were both sharper than the breakthrough front for NaX beads. This indicates that the flow distribution in the structured adsorbents is more even and that the mass-transfer resistance in the film is very low because of the small film thickness and high effective diffusivity for CO2 in the NaX film. Experimental data were used to obtain overall mass-transfer linear-driving-force constants, which were subsequently used in a numerical simulation program to estimate the performance of the adsorbents for CO2/N2 separation in a VSA process. It was found that the recovery of structured adsorbents was superior to that of a packed bed because of the much shorter mass-transfer zone. The purity, on the other hand, was not as high as that obtained with a packed bed because of excessive voidage in the structured adsorbents. Increased cell density or improved zeolite loading of the structured adsorbents would improve the CO2 purity without sacrificing recovery for the structured adsorbents, and this represents a path forward to improved VSA performance for CO2 capture.

  • 8. Rezaei, Fateme
    et al.
    Webley, Paul
    Monash University, Melbourne, VIC.
    Optimum structured adsorbents for gas separation processes2009In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 64, p. 5182-5191Article in journal (Refereed)
    Download full text (pdf)
    FULLTEXT01
  • 9. Rezaei, Fateme
    et al.
    Webley, Paul
    Monash University, Melbourne, VIC.
    Structured adsorbents in gas separation processes2010In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 70, p. 243-256Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 10. Rezaei, Fateme
    et al.
    Webley, Paul
    Monash University, Melbourne, VIC.
    Thermal Management of Structured Adsorbents in Gas Separation Processes2010Conference paper (Other academic)
  • 11. Rezaei, Fateme
    et al.
    Ynus, R.
    Ibrahim, N.A.
    Effect of fiber length on thermomechanical properties of short carbon fiberreinforced polypropylene composites2009In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 30, p. 260-263Article in journal (Refereed)
  • 12. Rezaei, Fateme
    et al.
    Ynus, R.
    Ibrahim, N.A.
    Mahdi, E.S.
    Development of Short-Carbon-Fiber-ReinforcedPolypropylene Composite for Car Bonnet2008In: Polymer-plastics technology and engineering (Softcover ed.), ISSN 0360-2559, E-ISSN 1525-6111, Vol. 47, p. 351-357Article in journal (Refereed)
  • 13.
    Rownaghi, Ali
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rezaei, Fateme
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Selective formation of light olefin by n-hexane cracking over HZSM-5: influence of crystal size and acid sites of nano- and micrometer-sized crystals2012In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 191, p. 528-533Article in journal (Refereed)
    Abstract [en]

    A series of HZSM-5 catalysts with different characteristics (size, texture, surface acid site density) was prepared by hydrothermal method and their performances were investigated in catalytic cracking of n-hexane (as a model compound of light naphtha) at 370 and 470 ˚C. Uniform nano-sized HZSM-5 (ca.∼ 0.1 μm) was found to be a very attractive catalyst, showing a selective formation of propylene and light olefin (about 83% at WHSV = 3 h−1) and a high resistance to the deactivation. Under similar conditions micro-size HZSM-5 (ca.∼ 2.0 μm) produced higher amount of other hydrocarbons i.e., C5+) and coke. This is because nano-size crystals have a larger external surface area, which offers a higher number of pore entrances and enhances the reaction occurring inside the pore channels compared with large miro-size crystals. In addition, it is found that the selectivity to light olefin increases by decreasing the number of acid sites on the external surface. This leads to the conclusion that in n-hexane cracking to light olefin, the activity and selectivity are related to the crystal size and the ratio of surface acid sites to total acid sites. As shown, reducing crystal size and decreasing acid sites on the external surface are remarkable ways to enhance catalytic activity and selectivity, respectively.

  • 14.
    Rownaghi, Ali
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rezaei, Fateme
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Uniform mesoporous ZSM-5 single crystals catalyst with high resistance to coke formation for methanol deoxygenation2012In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 151, p. 26-33Article in journal (Refereed)
    Abstract [en]

    In this study, an efficient procedure for controllable synthesis of uniform mesoporous ZSM-5 single crystals with various crystal architectures and high mesoporosity was developed. Compared with conventional ZSM-5 catalyst, mesoporous ZSM-5 single crystals synthesized by this method exhibited significantly higher external surface area and larger mesopore volume than conventional one. The catalytic performance of mesoporous zeolites were evaluated in the conversion of methanol to hydrocarbons using a fixed-bed reactor operating at 370 °C, atmospheric pressure and weight hourly space velocities (WHSV) of 0.16 to 6.58 h−1. By controlling the ZSM-5 synthesis procedure, the activity and stability of the ZSM-5 catalyst in the conversion of methanol to gasoline-range hydrocarbons can be favorably tuned. We also found that mesoporosity plays a crucial role in catalyst stability. Good correlation was observed between catalyst lifetime and mesoporosity. While the catalyst activity is related to the acid site density, the catalyst stability (deactivation rate) correlates with the measured surface ratio of BET and external surface area (SBET/SMeso). The novel ZSM-5 catalyst exhibited improved stability due to the faster removal of products with shorter diffusion path-length and lower coke formation. The obtained results indicated that the novel mesoporous ZSM-5 catalyst containing relatively large pores (mostly mesopores) enhances reaction yield towards gasoline-range hydrocarbons. It is therefore concluded that the relatively slow deactivation rate (coke formation) of novel mesoporous ZSM-5 single crystals catalyst makes this zeolite the preferred catalyst for the conversion of methanol to gasoline-range hydrocarbons at mild conditions.

  • 15.
    Rownaghi, Ali
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rezaei, Fateme
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Yield of gasoline-range hydrocarbons as a function of uniform ZSM-5 crystal size2011In: Catalysis communications, ISSN 1566-7367, E-ISSN 1873-3905, Vol. 14, no 1, p. 37-41Article in journal (Refereed)
    Abstract [en]

    Uniform ZSM-5 nanocrystals were synthesized by a single-templating procedure. The samples were then characterized by a variety of physical techniques such as XRD, SEM, BET, ICP and TPD. The dehydration of methanol over synthesized ZSM-5 zeolite was studied in a fixed-bed continuous flow reactor at 370 °C and WHSV of 2.6 gg−1 h under ambient pressure. The effect of crystal size of zeolite catalysts on product distribution in methanol dehydration reaction was investigated. Good correlation was observed between catalytic performance, product distribution and size of ZSM-5 crystals. It was found that the decrease in crystal size significantly influences light olefins (ethylene and propylene) and paraffins (C1–C4) selectivity in methanol dehydration reaction. Furthermore, nanocrystal ZSM-5 showed long-term catalytic stability compared with conventional ZSM-5 provided that the reaction activity is strongly dependent on the crystal size in methanol dehydration process. The results indicated that crystal size significantly affects the catalyst lifetime and hydrocarbon distributions in product stream. Based on the obtained results, it is concluded that the use of uniform ZSM-5 nanocrystals improves the yield of propylene and alkyl aromatics in methanol conversion reaction at mild conditions.

  • 16.
    Rownaghi, Ali
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rezaei, Fateme
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Stante, Matteo
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Selective dehydration of methanol to dimethyl ether on ZSM-5 nanocrystals2012In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 119-120, no 7, p. 56-61Article in journal (Refereed)
    Abstract [en]

    The effects of crystal size and mesoporosity on the performance of various synthesized ZSM-5 zeolites in catalytic dehydration of methanol to dimethyl ether (DME) reaction have been investigated. The reactions were carried out in a continuous flow fixed-bed reactor at temperatures between 180 to 320 °C and 1.1 bar. It was found that methanol conversion enhances by decreasing crystal size and increasing the reaction temperature. Uniform nanocrystal catalysts showed highest activity and stability for methanol dehydration to dimethyl ether in the temperature range studied. On the other hand, both the activity and selectivity of large crystals were low. The high activity and DME yield for the nanocrystals is due to smaller mass transport resistance for the Nano-ZSM-5 sample, due to the small crystal size. Furthermore, it was found that the selective dehydration of methanol to dimethyl ether on ZSM-5 catalyst is based on the product selectivity inside the pore channels; in other words, the selectivity to dimethyl ether should be 100% if there is no acid site on the external surface. From this evidence, it is concluded that in methanol dehydration to DME, the reaction activity is related to the crystal size, whereas the DME selectivity is determined by the uniformity of Al distribution, which determines acidity of external surface and low mass transport resistance of small crystal size. Therefore, a decrease in the number of acid sites on the external surface and reduction in crystal size are key ways to enhance catalytic selectivity and activity, respectively.

  • 17.
    Rownaghi, Ali
    et al.
    Monash University, Melbourne, VIC.
    Taufiq-Yap, Yun Hin
    Rezaei, Fateme
    High Surface Area Vanadium Phosphate Catalysts for n-Butane Oxidation2009In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 48, no 16, p. 7517-7528Article in journal (Refereed)
  • 18. Rownaghi, Ali
    et al.
    Taufiq-Yap, Yun Hin
    University Putra Malaysia.
    Rezaei, Fateme
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Innovative process for the synthesis of vanadyl pyrophosphate as a highly selective catalyst for n-butane oxidation2010In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 165, no 1, p. 328-335Article in journal (Refereed)
    Abstract [en]

    Vanadyl pyrophosphate (VPO) catalysts are used for the selective oxidation of light alkanes, which are based on vanadyl hydrogen phosphate hemihydrate (VOHPO40.5H2O) as the precursor. Catalyst precursor with well-defined crystal size has been successfully synthesized for the first time, using a simple one-step high-pressure autoclave that was surfactant-free and water-free method with significantly lower temperature and shorter reaction time. VOHPO40.5H2O was prepared from V2O5 using an isobutanol, 1-pentanol, 1-heptanol and 1-dectanol as both solvent and reducing agent at elevated temperatures (100, 120, and 150°C). This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO40.5H2O) when compared to conventional hydrothermal synthesis methods. VOHPO40.5H2O can be obtained at temperature far below 150°C. It was found that the presence of 1-heptanol and 1-decanol in the reaction mixtures is crucial for obtaining a well-defined crystal size of precursor phase and solely generated impurity, [VO(H2PO4)2]. Our findings show that both the phase composition and morphology of vanadium phosphate can be influenced by the use of different reducing agent and temperature during the preparation process. This new methodology produces catalysts with a much higher surface area (ca. 23m2g-1) compared with those materials prepared by slow hydrothermal synthesis (ca. 9.5m2g-1). Finally, the yield of maleic anhydride was significantly increased from 21.3% for conventional catalyst to 37.9% for the new solvothermal catalyst.

  • 19.
    Rownaghi, Ali
    et al.
    Monash University, Melbourne, VIC.
    Taufiq-Yap, Yun Hin
    Rezaei, Fateme
    Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation2009In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 155, no 1-2, p. 514-522Article in journal (Refereed)
    Abstract [en]

    In this paper, we have developed a simple, low-cost, template-free and surfactant-free solvothermal process for synthesis of vanadyl hydrogen phosphate hemihydrate (VOHPO4·0.5H2O) with well defined crystal size. The synthesis was performed by reaction of VPO4·2H2O with an aliphatic alcohol (isobutyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol or 1-decanol). This afforded well crystallized VOHPO4·0.5H2O by solvothermal methods at 120°C temperature. This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO4·0.5H2O) when compared to conventional hydrothermal synthesis methods. By varying the reducing agent, the solvothermal evolution process from layered tetragonal phase VOPO4·2H2O to orthorhombic phase VOHPO4·0.5H2O was observed. It was found that the length of carbon chain in an alcohol in the solvothermal condition had a great impact on chemical and physical properties of resulting catalysts. Interestingly, there was no trace of VO(H2PO4)2an impurity noted to be readily formed under solvothermal preparation condition. Therefore, this study introduces a more facile synthetic pathway to V(III) compounds. In addition, the microwave-synthesized catalysts exhibited some properties superior to those of conventionally synthesized catalyst such as better stability, crystallinity, and catalytic activity in the production of maleic anhydride. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), N2physisorption, temperature programmed reduction (H2-TPR) and scanning electron microscopy (SEM). The XRD pattern of the active catalyst prepared by this solvothermal method confirmed the presence of smaller crystal size (between 6 and 13nm along 020 planes) of vanadium phosphate catalyst with higher specific surface area. Finally, the yield of maleic anhydride was significantly increased from 29% for conventional catalyst to 44% for the new solvothermal catalyst.

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