Publications
186 results found
Graca I, Iruretagoyena D, Chadwick D, 2017, Glucose isomerisation into fructose over magnesium-impregnated NaY zeolite catalysts, Applied Catalysis B: Environmental, Vol: 206, Pages: 434-443, ISSN: 0926-3373
The performance of magnesium-impregnated NaY zeolite catalysts for the glucose isomerisation into fructose at 100 °C has been evaluated. Although crystallinity and textural properties of the zeolites are reduced through Mg addition, glucose conversion improves (6–49%) by increasing magnesium content (0–15 wt.%) due to an increase of the number of basic sites. Conversely, selectivity to fructose drops (96–66%). Nevertheless, good fructose yields were still reached with 10 and 15 wt.% of magnesium (about 32%), being similar or even higher than those found for a commercial hydrotalcite and a pure magnesium oxide. Catalysts lose performance through carbon retention and cations leaching. Deactivation of magnesium-based zeolites was further investigated by consecutive reaction runs. If no regeneration of the catalyst is performed, the activity of the zeolites decreases mainly as a result of cations leaching, the effect reducing with the number of runs. Regeneration allows the catalyst to recover almost totally its initial activity. Interestingly, used samples show higher fructose selectivity due to the additional pore opening resulting from cations leaching and/or carbon removal. Cations leaching results in a homogeneous catalytic reaction which is most significant for the highest magnesium content. Magnesium-based NaY zeolites are revealed as potential catalysts for glucose isomerisation into fructose with high fructose productivities and good performance in consecutive reactions combined with intermediate regeneration.
Shin SB, Lee D-W, Chadwick D, 2017, Epoxidation of propene in a confined Taylor flow (CTF) reactor at atmospheric pressure, CHEMICAL ENGINEERING RESEARCH & DESIGN, Vol: 121, Pages: 305-314, ISSN: 0263-8762
Heterogeneous catalytic epoxidation of propene to propene oxide with hydrogen peroxide as oxidant was investigated in a confined Taylor flow (CTF) reactor, a continuous monolith reactor, containing a long alumina rod coated with titanium silicalite (TS-1) catalyst in the centre of the reactor column. The effect of gas and liquid superficial velocity on the hydrodynamics of CTF reactor was also investigated under Taylor flow regime at atmospheric pressure. The variation of hydrodynamics had a profound impact on the production of propene oxide. When liquid superficial velocity was constant, the concentration of propene oxide produced decreased with increasing gas superficial velocity as Taylor bubble length and bubble rise velocity increase. However, when gas superficial velocity was constant, the concentration of propene oxide produced had no linear dependency on liquid superficial velocity as Taylor bubble length decreases but bubble rise velocity increases.
Khawaji M, Chadwick D, 2017, Highly active Au-Pd nanoparticles supported on titanate nanotubes, 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Al-Shihri S, Richard CJ, Chadwick D, 2017, Selective Oxidation of Methane to Methanol over ZSM-5 Catalysts in Aqueous Hydrogen Peroxide: Role of Formaldehyde, CHEMCATCHEM, Vol: 9, Pages: 1276-1283, ISSN: 1867-3880
The selective oxidation of methane in aqueous hydrogen peroxide over ZSM-5 catalysts with different Si/Al ratios has been investigated. Methyl hydroperoxide was confirmed as the initial product of methane oxidation by a study of product distribution versus reaction time in agreement with previous work. Formaldehyde was identified as an intermediate in the oxidation reaction pathway from MeOOH to formic acid and ultimately CO2. Hydrogen evolution during the oxidation of methane is reported for the first time. Oxidation of the HCHO intermediate to formic acid was demonstrated to be the source of the evolved hydrogen. HCHO appeared to be the source of low levels of soluble polyoxomethylene. Higher productivity of liquid oxygenated products is reported compared to previous work.
Shin SB, Lee D-W, Chadwick D, 2016, The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide, Journal of Molecular Catalysis A-Chemical, Vol: 423, Pages: 478-488, ISSN: 1381-1169
Propene oxide is an important chemical intermediate and titanium silicalite (TS-1) has been widely investigated as a promising catalyst for the direct epoxidation of propene with ex-situ or in-situ produced hydrogen peroxide as an oxidant. In order to clarify the effects of the kind of precious metal and treatment process in the catalyst preparation on the propene epoxidation and the hydrogen peroxide decomposition, TS-1 was impregnated with gold and palladium via drying, calcination and reduction and the experiments to check its catalytic performance were conducted in a gas aspirating autoclave reactor in the absence of mass transfer limitations. The presence of precious metals vigorously catalyzed the side reactions and hydrogen peroxide decomposition. Some of the precious metal containing TS-1 catalysts showed high initial rates but there was no catalyst with a propene oxide yield after 5 h reaction time comparable to TS-1 alone because of the enhancement of side reactions by precious metals. The significant decline in the selectivity to propene oxide over the dried precious metal containing TS-1 catalysts was attributed to the leaching of precious metals into the reaction medium. Palladium containing TS-1 showed exceptionally high decomposition of hydrogen peroxide. Reduction and calcination increased the decomposition by forming metallic gold and palladium. Homogeneous dispersion of gold nanoparticles was achieved by a sol immobilization method which led to a decrease of propene oxide selectivity and an increase of hydrogen peroxide decomposition.
Chadwick D, 2016, Supported Layered Double Hydroxides as CO<sub>2</sub> Adsorbents for Sorption-enhanced H<sub>2</sub> Production Supervisor's Foreword, SUPPORTED LAYERED DOUBLE HYDROXIDES AS CO2 ADSORBENTS FOR SORPTION-ENHANCED H2 PRODUCTION, Publisher: SPRINGER INTERNATIONAL PUBLISHING AG, Pages: VII-VIII, ISBN: 978-3-319-41275-7
Iruretagoyena D, Huang X, Shaffer MSP, et al., 2015, Influence of Alkali Metals (Na, K, and Cs) on CO2 Adsorption by Layered Double Oxides Supported on Graphene Oxide, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 54, Pages: 11610-11618, ISSN: 0888-5885
Gil AG, Wu Z, Chadwick D, et al., 2015, Ni/SBA-15 Catalysts for combined steam methane reforming and water gas shift-Prepared for use in catalytic membrane reactors, APPLIED CATALYSIS A-GENERAL, Vol: 506, Pages: 188-196, ISSN: 0926-860X
Ortega-Dominguez RA, Mendoza-Nieto JA, Hernandez-Hipolito P, et al., 2015, Influence of Na content on behavior of NiMo catalysts supported on titania nanotubes in hydrodesulfurization, JOURNAL OF CATALYSIS, Vol: 329, Pages: 457-470, ISSN: 0021-9517
Iruretagoyena D, Shaffer MSP, Chadwick D, 2015, Layered Double Oxides Supported on Graphene Oxide for CO2 Adsorption: Effect of Support and Residual Sodium, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 54, Pages: 6781-6792, ISSN: 0888-5885
Gil AG, Wu Z, Chadwick D, et al., 2015, A catalytic hollow fibre membrane reactor for combined steam methane reforming and water gas shift reaction, Chemical Engineering Science, Vol: 137, Pages: 364-372, ISSN: 0009-2509
A catalytic hollow fibre membrane reactor (CHFMR) was developed in this study for combined steam methane reforming (SMR) and water gas shift (WGS) reaction. This is achieved by incorporating a Ni/SBA-15 catalyst into a plurality of micro-channels with open entrance from inner surface of Al2O3 hollow fibres, followed by coating of a 3.3 µm Pd membrane on the outer surface of the hollow fibre using an electroless plating method. In addition to systematic characterizations of each reactor component, i.e. Ni/SBA-15 catalyst, micro-structured ceramic hollow fibre and Pd separating layer, the effect of how the reactor was assembled or fabricated on the catalytic performance was evaluated. Electroless plating of the Pd membrane impaired the catalytic performance of the deposited Ni/SBA-15 catalyst. Also, the over-removal of hydrogen from the reaction zone was considered as the main reason for the deactivation of the Ni-based catalyst. Instead of mitigating such deactivation using “compensating” hydrogen, starting the reaction at higher temperatures was found more efficient in improving the reactor performance, due to a better match between hydrogen production (from the reaction) and hydrogen removal (from the Pd membrane). An effective methane conversion of approximately 53%, a CO2 selectivity of 94% and a H2 recovery of 43% can be achieved at 560 °C. In order for a more significant “shift” phenomenon, alternative methodology of fabricating the reactor and more coke resistant catalysts are recommended.
Gil AG, Wu Z, Chadwick D, et al., 2015, Microstructured Catalytic Hollow Fiber Reactor for Methane Steam Reforming, Industrial & Engineering Chemistry Research, Vol: 54, Pages: 5563-5571, ISSN: 1520-5045
Microstructured alumina hollow fibers, which contain a plurality of radial microchannels with significant openings on the inner surface, have been fabricated in this study and used to develop an efficient catalytic hollow fiber reactor. Apart from low mass-transfer resistance, a unique structure of this type facilitates the incorporation of Ni-based catalysts, which can be with or without the aged secondary support, SBA-15. In contrast to a fixed bed reactor, the catalytic hollow fiber reactor shows similar methane conversion, with a gas hourly space velocity that is approximately 6.5 times higher, a significantly greater CO2 selectivity, and better productivity rates. These results demonstrate the advantages of dispersing the catalyst inside the microstructured hollow fiber as well as the potential to reduce the required quantity of catalyst.
Sharifzadeh M, Richard CJ, Liu K, et al., 2015, An integrated process for biomass pyrolysis oil upgrading: A synergistic approach, Biomass & Bioenergy, Vol: 76, Pages: 108-117, ISSN: 0961-9534
Gil AG, Reis MHM, Chadwick D, et al., 2015, A highly permeable hollow fibre substrate for Pd/Al<sub>2</sub>O<sub>3</sub> composite membranes in hydrogen permeation, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 40, Pages: 3249-3258, ISSN: 0360-3199
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- Citations: 27
Torrente-Murciano L, Villager T, Chadwick D, 2015, Selective Oxidation of Salicylic Alcohol to Aldehyde with O<sub>2</sub>/H<sub>2</sub> using Au-Pd on Titanate Nanotubes Catalysts, CHEMCATCHEM, Vol: 7, Pages: 925-927, ISSN: 1867-3880
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- Citations: 26
Torrente-Murciano L, He Q, Hutchings GJ, et al., 2014, Enhanced Au-Pd Activity in the Direct Synthesis of Hydrogen Peroxide using Nanostructured Titanate Nanotube Supports, CHEMCATCHEM, Vol: 6, Pages: 2531-2534, ISSN: 1867-3880
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- Citations: 30
Sitthikhankaew R, Chadwick D, Assabumrungrat S, et al., 2014, Effects of humidity, O<sub>2</sub>, and CO<sub>2</sub> on H<sub>2</sub>S adsorption onto upgraded and KOH impregnated activated carbons, FUEL PROCESSING TECHNOLOGY, Vol: 124, Pages: 249-257, ISSN: 0378-3820
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- Citations: 68
Montesano R, Narvaez A, Chadwick D, 2014, Shape-selectivity effects in syngas-to-dimethyl ether conversion over Cu/ZnO/Al<sub>2</sub>O<sub>3</sub> and zeolite mixtures: Carbon deposition and by-product formation, APPLIED CATALYSIS A-GENERAL, Vol: 482, Pages: 69-77, ISSN: 0926-860X
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- Citations: 27
Sitthikhankaew R, Chadwick D, Assabumrungrat S, et al., 2014, Effect of KI and KOH Impregnations over Activated Carbon on H<sub>2</sub>S Adsorption Performance at Low and High Temperatures, SEPARATION SCIENCE AND TECHNOLOGY, Vol: 49, Pages: 354-366, ISSN: 0149-6395
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- Citations: 24
Sitthikhankaew R, Chadwick D, Assabumrungrat S, et al., 2014, Performance of Sodium-Impregnated Activated Carbons toward Low and High Temperature H<sub>2</sub>S Adsorption, CHEMICAL ENGINEERING COMMUNICATIONS, Vol: 201, Pages: 257-271, ISSN: 0098-6445
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- Citations: 13
Iruretagoyena D, Shaffer MSP, Chadwick D, 2014, Adsorption of carbon dioxide on graphene oxide supported layered double oxides, ADSORPTION-JOURNAL OF THE INTERNATIONAL ADSORPTION SOCIETY, Vol: 20, Pages: 321-330, ISSN: 0929-5607
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- Citations: 30
Narvaez A, Chadwick D, Kershenbaum L, 2014, Small-medium scale polygeneration systems: methanol and power production, Applied Energy, Vol: 113, Pages: 1109-1117, ISSN: 0306-2619
The feasibility and attractiveness of the integrated production of chemicals and electrical power is dependent upon on the nature of the products and their demands. This study focuses on the small-to-medium scale combined production of methanol (200,000 tonnes/year) and electrical power (200 MW). The integrated system considers both recycle (recycle ratio = 5) and once-through (no recycle) modes of methanol synthesis. The results of simulations show that, when compared to separate stand-alone plants for methanol and power production, the integrated systems show lower consumption of total fresh synthesis gas for recycle and once-through operation of 2.8% and 3.7%, respectively. In addition, simulations show that the advantage over stand-alone plants increases further in the face of decreasing catalyst activity or selectivity, rising to over 10% in several scenarios. This is because the off-spec material from methanol production in an integrated plant can be diverted to the power generation section of the plant. These savings in operating costs are over and above the substantial capital cost savings which can be realized in the design of a once-through integrated plant.
Azizan MT, Hellgardt K, Chadwick D, 2014, Ethanol Steam Reforming Over Calcium Doped Ni/Al<sub>2</sub>O<sub>3</sub> Catalyst, 3rd International Conference on Process Engineering and Advanced Materials (ICPEAM), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 271-+, ISSN: 1660-9336
Azizan MT, Hellgardt K, Chadwick D, 2014, Thermodynamic Analysis of Autothermal Reforming of Oxygenated Hydrocarbons At Thermoneutral Condition for Hydrogen Production, 3rd International Conference on Process Engineering and Advanced Materials (ICPEAM), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 730-+, ISSN: 1660-9336
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- Citations: 6
Richard CJ, Patel B, Chadwick D, et al., 2013, Hydrothermal deoxygenation of pyrolysis oil from Norwegian spruce: <i>Picea abies</i>, BIOMASS & BIOENERGY, Vol: 56, Pages: 446-455, ISSN: 0961-9534
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- Citations: 9
Ryabenkova Y, He Q, Miedziak PJ, et al., 2013, The selective oxidation of 1,2-propanediol to lactic acid using mild conditions and gold-based nanoparticulate catalysts, CATALYSIS TODAY, Vol: 203, Pages: 139-145, ISSN: 0920-5861
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- Citations: 57
Torrente-Murciano L, Gilbank A, Puertolas B, et al., 2013, Shape-dependency activity of nanostructured CeO<sub>2</sub> in the total oxidation of polycyclic aromatic hydrocarbons, APPLIED CATALYSIS B-ENVIRONMENTAL, Vol: 132, Pages: 116-122, ISSN: 0926-3373
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- Citations: 148
Garcia-Gallastegui A, Iruretagoyena D, Gouvea V, et al., 2012, Graphene Oxide as Support for Layered Double Hydroxides: Enhancing the CO<sub>2</sub> Adsorption Capacity, CHEMISTRY OF MATERIALS, Vol: 24, Pages: 4531-4539, ISSN: 0897-4756
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- Citations: 194
Montesano R, Chadwick D, 2012, Combined methanol and dimethyl ether synthesis from CO/H<sub>2</sub>: Phosphorus mediated deactivation, CATALYSIS COMMUNICATIONS, Vol: 29, Pages: 137-140, ISSN: 1566-7367
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- Citations: 10
Garcia-Garcia FR, Torrente-Murciano L, Chadwick D, et al., 2012, Hollow fibre membrane reactors for high H<sub>2</sub> yields in the WGS reaction, JOURNAL OF MEMBRANE SCIENCE, Vol: 405, Pages: 30-37, ISSN: 0376-7388
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- Citations: 32
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