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  • 1.
    Ahlkvist, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ajaikumar, Samikannu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    One-pot catalytic conversion of Nordic pulp media into green platform chemicals2013Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 454, s. 21-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, both sulphite and sulphate (Kraft) cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice was a macro-porous, cationic ion-exchange resin, Amberlyst 70. The optimal reaction conditions were determined and the influence of various gas atmospheres was investigated. The maximum yields of 53% formic acid and 57% of levulinic acid were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively.

  • 2.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ahlkvist, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FIN-20500, Turku/Åbo, Finland.
    Oxidation of α-pinene over gold containing bimetallic nanoparticles supported on reducible TiO2 by DPU method2011Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, nr 1-2, s. 11-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of bimetallic catalysts Au–M (where M = Cu, Co and Ru) were supported on a reducible TiO2 oxide via deposition-precipitation (DP) method with a slow decomposition of urea as the precipitating agent. The characteristic structural features of the prepared materials were characterized by various physico-chemical techniques such as X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XPS results indicated the formation of alloyed bimetallic particles on the TiO2 support. TEM results confirmed the fine dispersion of metal nanoparticles on the support with an average particle size in the range of 3–5 nm. An industrially important process, oxy-functionalization of α-pinene was carried out over the prepared bimetallic heterogeneous catalysts under liquid phase conditions. Reaction parameters such as the reaction time, temperature, and the effect of solvent were studied for optimal conversion of α-pinene into verbenone. The major products obtained were verbenone, verbenol, α-pinene oxide and alkyl-pinene peroxide. The activity of the catalysts followed the order; AuCu/TiO2 > AuCo/TiO2 > Cu/TiO2 > Au/TiO2 > AuRu/TiO2. Upon comparison of the various catalysts, AuCu/TiO2 was found to be an active and selective catalyst towards the formation of verbenone. The temperature, nature of the catalysts and the choice of solvents greatly influenced the reaction rate.

  • 3.
    Bukhanko, Natalia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Forest Biomaterials Technology, Swedish University of Agricultural Science, Umeå, Sweden.
    Schwarz, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ngoc Pham, Tung
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Chemistry, The University of Danang - University of Science and Technology, Nguyen Luong Bang, Lien Chieu, Da Nang, Viet Nam.
    Siljebo, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wärnå, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rautio, Anne-Riikka
    Kordas, Krisztian
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts2017Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 542, nr 25, s. 212-225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isopropyl chloride synthesis from isopropanol and HCl in gas phase over ZnCl2 catalysts supported on Al2O3 as well as flexible carbon foam was studied in a continuous reactor. A series of catalytic materials were synthesised and characterised by BET, XPS, SEM, TEM, XRD and NH3-TPD methods. Catalytic activity tests (product selectivity and conversion of reactants) were performed for all materials and optimal reaction conditions (temperature and feedstock flow rates) were found. The results indicate that the highest yield of isopropyl chloride was obtained over 5 wt.% ZnCl2 on commercial Al2O3 (No. II) (95.3%). Determination of product mixture compositions and by-product identification were done using a GC-MS method. Carbon foam variant catalyst, 5 wt.% ZnCl2/C, was found to perform best out of the carbon-supported materials, achieving ∼75% yield of isopropyl chloride. The kinetic model describing the process in a continuous packed bed reactor was proposed and kinetic parameters were calculated. The activation energy for the formation of isopropyl chloride reaction directly from isopropanol and HCl was found to be ∼58 kJ/mol.

  • 4.
    Eta, Valerie
    et al.
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku/Åbo, Finland.
    Mäki-Arvela, Päivi
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku/Åbo, Finland.
    Wärnå, Johan
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku/Åbo, Finland.
    Salmi, Tapio
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku/Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Murzin, Dmitry Yu
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku/Åbo, Finland.
    Kinetics of dimethyl carbonate synthesis from methanol and carbon dioxide over ZrO2–MgO catalyst in the presence of butylene oxide as additive2011Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 404, nr 1-2, s. 39-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A kinetic investigation of dimethyl carbonate (DMC) synthesis from methanol and CO2 over ZrO2–MgO was performed by using butylene oxide as a chemical trap for the water formed during the reaction. The effect of the catalyst amount, the stirring speed, the temperature, as well as the amount of butylene oxide on the reaction rate and the selectivity to DMC was studied. The analysis of the reaction pathway suggests that DMC and butylene glycol are formed via the reaction of adsorbed mono-methoxycarbonate intermediate and methoxybutanol or methanol. A kinetic model was developed based on the reaction mechanism and it was in agreement with the experimental data. The apparent activation energy for the formation of DMC was 62 kJ/mol.

  • 5.
    Golets, Mikhail
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Blomberg, David
    Processum Biorefinery Initiative AB, SE-89186, Örnsköldsvik, Sweden.
    Grundberg, H
    Aditya Birla Domsjö Fabriker AB, SE-89186, Örnsköldsvik, Sweden.
    Wärnå, J
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Salmi, T
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Liquid phase acetoxylation of α-pinene over Amberlyst-70 ion-exchange resin2012Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 435-436, s. 43-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Heterogeneously-catalyzed and solvent-catalyzed liquid phase acetoxylation of α-pinene with acetic acid acting as both a solvent and a reagent was studied. Both solvent-catalyzed and catalytic experiments were carried out and various reaction conditions were studied. The influence of temperature, pressure, solvent and gas milieu were taken into account. Bornyl, fenchyl, verbenyl as well as α-terpinyl acetates, limonene, camphene and γ-terpinene were found among reaction products. The addition of the catalyst allowed for maximization of the yield of bornyl acetate. The predominant products obtained were α-terpinyl, verbenyl and bornyl acetates. The reaction pathways were identified and evaluated.

    The aim of this work was to study of the feasibility of batch acetoxylation of alpha-pinene. The analysis of the complex product distribution is not trivial and, consequently, resolving the reaction network was important. The optimized reaction conditions were searched for aiming at an efficient conversion of α-pinene to a mixture of valuable products.

  • 6. Jogunola, Olatunde
    et al.
    Salmi, Tapio
    Eränen, Kari
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Qualitative treatment of catalytic hydrolysis of alkyl formates2010Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 384, nr 1-2, s. 36-44Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Liquid-phase hydrolysis of alkyl formates was performed in a stirred batch reactor using formic acid as a homogenous catalyst, cation exchange resin as heterogeneous catalyst and an additive as a complexation agent. The catalysts increased the rate of the reaction considerably, but the equilibrium conversion was slightly suppressed by the homogenous catalyst. The additive not only accelerated the reaction rate, but also improved the yield significantly. The effect of external and internal mass transfer limitations present in the heterogeneous reaction steps was investigated and it was observed that there is the existence of internal diffusion limitation for the largest catalyst particles. Other parameters such as temperature, catalyst pre-treatment, catalyst loading and stirring speed were investigated in order to optimize the process. The experiments also demonstrated that the ion exchange resin can be reused more than once.

  • 7. Kirilin, Alexey V
    et al.
    Tokarev, Anton V
    Kustov, Leonid M
    Salmi, Tapio
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Murzin, Dmitry Yu
    Aqueous phase reforming of xylitol and sorbitol: comparison and influence of substrate structure2012Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 435-436, s. 172-180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The behavior of abundant polyol stemming from hemicelluloses, xylitol, was investigated in the aqueous phase reforming (APR) over supported Pt/Al2O3. The data obtained in the case of xylitol was compared to aqueous phase reforming of sorbitol under the same operating conditions. The effect of weight hour space velocity on the performance of a catalytic system as well as on selectivity towards hydrogen and alkanes was studied. The catalyst showed stable performance with insignificant deactivation over 160 hours time-on-stream. The selectivity towards H2 diminished from 86 to 70% within 120 hours. The regeneration of the catalytic system in a H2 flow allowed to recover the catalyst activity and to improve selectivity towards H2 to 75%. It was found that both polyols demonstrated similar behavior in the APR in the whole range of space velocities studied. The selectivity towards H2 went through a maximum in the case of xylitol and sorbitol when changing a space velocity. This behavior was attributed to a number of side reactions which involved hydrogen thus leading to its consumption. Additionally, the yields of target APR product, hydrogen, were higher in the case of xylitol compared to sorbitol due to the longer carbon chain in the latter substrate. The plausible reaction network based on the hypothesis that APR process proceeds through the terminal position of polyol was proposed to explain similarity in the gas and liquid product composition in the APR of xylitol and sorbitol. The reaction scheme describing formation of the main gas and liquid products via various pathways was proposed and discussed. The results obtained and explanations provided are in perfect coincidence with the results obtained for different substrates in the literature.

  • 8.
    Konwar, Lakhya Jyoti
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Council of Scientific & Industrial Research (CSIR), G. B. Marg, Gujarat, Bhavnagar, India.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Carbon support effects on metal (Pd, Pt and Ru) catalyzed hydrothermal decarboxylation/deoxygenation of triglycerides2022Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 638, artikel-id 118611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein, we show that textural properties of carbon supports have limited influence on the activity and stability of carbon supported Pd, Pt and Ru catalysts upon decarboxylation of a model triglyceride (tristearin) in the presence of subcritical water (256–326 °C). In contrast, surface acid-base properties of carbon supports were found to have a marked impact on the performance and stability of these catalysts. More precisely, for Pt group (Pt and Pd) a positive correlation could be observed between the concentration of surface basic sites and catalyst deoxygenation activity and durability while acid sites had the opposite effect. On the other hand, the activity of Ru-based catalysts were not analogously affected by the acid-base properties of carbon supports, even so a positive correlation was found between surface basicity and durability (reusability). Further, the activity of metals in decreasing order of TOF was Ru>Pt>Pd, irrespective of carbon support.

  • 9. Leino, E
    et al.
    Mäki-Arvela, P
    Eta, V
    Murzin, D Yu
    Salmi, T
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Conventional synthesis methods of short-chain dialkylcarbonates and novel production technology via direct route from alcohol and waste CO22010Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 383, nr 1-2, s. 1-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this work is to review different synthesis methods of dialkylcarbonates with special emphasis on diethyl carbonate synthesis methodologies. The novel synthesis route for dimethyl carbonate and diethyl carbonate based on the utilization of alcohol and carbon dioxide as the raw materials, together with heterogeneous catalysts, is presented.

     

  • 10. Mani, Mariappan
    et al.
    Mariyaselvakumar, Mariyamuthu
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Panda, Asit Baran
    Konwar, Lakhya Jyoti
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland .
    Continuous hydrocyclization of aqueous levulinic acid to γ-valerolactone over bi-functional Ru/NbOPO4/SBA-15 catalyst under mild conditions2022Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 643, artikel-id 118744Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein, we demonstrate that surface acid-base properties have marked effect upon the performance (activity, selectivity and stability) of supported Ru catalysts upon tandem hydrocyclization (hydrogenation-dehydration) of aqueous levulinic acid. A mesoporous bi-functional Ru/NbOPO4/SBA-15 catalyst incorporating highly dispersed Ru sites and well balanced strong Brønsted acidic sites (optimum B/L and M+S/W ratio) was identified, which outperformed the benchmark monofuncational (Ru/SBA-15, Ru/MCM-41) and physically blended bi-functional catalysts (Ru catalysts mixed with acid co-catalysts e.g. NbOPO4/Amberlyst-15). Further, the catalyst also demonstrated remarkable stability in a fixed-bed reactor, maintaining steady activity and γ-valerolactone selectivity (72-86%) during ca. 300 h time on stream (10 bar, 90-100 oC), corroborating its industrial potential. The exceptional performance and durability of the bi-functional catalyst was attributed to the presence of well dispersed hydrothermally and chemically stable acid (NbOPO4) and redox (Ru) sites.

  • 11.
    Mariyaselvakumar, Mariyamuthu
    et al.
    Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), GB Marg, Bhavnagar, India; Department of Chemistry, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar, India.
    Kadam, Ganesh Govind
    Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), GB Marg, Bhavnagar, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
    Saha, Anusuya
    Analytical and Environmental Science Division and Centralized Instrument Facility, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), GB Marg, Bhavnagar, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Ganguly, Biswajit
    Analytical and Environmental Science Division and Centralized Instrument Facility, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), GB Marg, Bhavnagar, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
    Srinivasan, Kannan
    Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), GB Marg, Bhavnagar, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India; Department of Chemistry, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar, India.
    Konwar, Lakhya Jyoti
    Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research (CSIR), GB Marg, Bhavnagar, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
    Halogenated melamine formaldehyde polymers: Efficient, robust and cost-effective bifunctional catalysts for continuous production of cyclic carbonates via. CO2-epoxide cycloaddition2024Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 675, artikel-id 119634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Halogenated porous melamine polymers were demonstrated as an efficient catalyst for CO2-epoxide cycloaddition, selectively (>99%) producing C3-C12 cyclic carbonates in excellent yields (upto 99%) under solvent and co-catalyst free conditions. The halogenated polymers outperformed benchmark catalysts incorporating only basic (N-doped carbon, ZIF-8, N-rich melamine polymer) or nucleophilic (TBAB, KI) sites. The superior catalytic performance of these inexpensive polymers was attributed to their unique surface chemistry incorporating abundant, stable basic N sites (amine N and protonated N) and nucleophilic (Cl-, Br- or I-) that enabled simultaneous activation of both epoxide and CO2 molecule (supported by kinetic and DFT studies). Further, among halogenated polymers a Br- containing material (PMFBr) presented highest activity owing to its balanced CO2-philicity and strong nucleophilicity. Most importantly, PMFBr was robust, reusable and maintained stable performance for continuous production of C3-C4 cyclic carbonate (120 oC, 0.3-0.83 h-1 WHSVepoxide and 15 bar) in a fixed-bed reactor during 60-190 h TOS.

  • 12. Schmidt, Sabrina A.
    et al.
    Kumar, Narendra
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Eranen, Kari
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Murzin, Dmitry Yu.
    Salmi, Tapio
    Preparation and characterization of neat and ZnCl2 modified zeolites and alumina for methyl chloride synthesis2013Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 468, s. 120-134Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A range of zeolite and alumina based catalysts, neat and impregnated with ZnCl2, were screened for gas-phase methyl chloride synthesis from methanol and HCl. The catalysts were characterized with FTIR, TEM, XPS, N-2-physisorption, XRD and EDX to identify the relationship between the catalyst characteristics and their activity and selectivity in methyl chloride synthesis. The work was focused on catalyst performance and stability, acid properties of catalysts and the influence of zinc impregnation. Upon modification with ZnCl2, the number of strong and medium Bronsted acid sites (BAS) decreased, while the number of Lewis acid sites (LAS) increased. The zinc species detected on the catalyst surface is possibly similar to ZnOCl. The presence of ZnCl2 as surface species is not probable, as chlorine is partially removed from the catalyst during calcination at 400 degrees C. However, the binding energy determined by XPS suggests a Zn2+ surface species. Zn2+ containing particles were observed on zeolites by TEM, which show a dependence of the particle size on the support acidity. The activities of the catalysts increased with the number of medium and strong LAS, whereas the methyl chloride selectivity slightly decreased giving dimethyl ether as a by-product. As the increase of acid sites upon modification with the same amounts of ZnCl2 was most pronounced for zeolite catalysts, they exhibited the highest activity. However, the zeolite catalysts showed deactivation with time on stream. Zn/H-ZSM 5 zeolite catalysts exhibited a higher stability in the synthesis of methyl chloride than ZnCl2 modified H-Beta and could be regenerated by burning the coke in air at 400 degrees C. Neat alumina and ZnCl2 modified alumina catalysts were active and selective at 300 degrees C and higher temperatures, but zeolite catalysts might be suitable for methyl chloride synthesis at lower temperatures, i.e. 200 degrees C.

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