124-38-9

CO activation pathways and the mechanism of Fischer-Tropsch synthesis

Ojeda, Manuel,Nabar, Rahul,Nilekar, Anand U.,Ishikawa, Akio,Mavrikakis, Manos,Iglesia, Enrique

, p. 287 - 297 (2010)

Unresolved mechanistic details of monomer formation in Fischer-Tropsch synthesis (FTS) and of its oxygen rejection routes are addressed here by combining kinetic and theoretical analyses of elementary steps on representative Fe and Co surfaces saturated w

Photocatalytic reactions under irradiation of visible light over gold nanoparticles supported on titanium(IV) oxide powder prepared by using a multi-step photodeposition method

Tanaka, Atsuhiro,Sakaguchi, Satoshi,Hashimoto, Keiji,Kominami, Hiroshi

, p. 1931 - 1938 (2014)

Titanium(IV) oxide (TiO2) having both smaller and larger gold (Au) particles was successfully prepared by a multi-step (MS) photodeposition method. When 0.25 wt% Au loading per photodeposition was repeated four times, smaller and larger Au particles having average diameters of 1.4 and 13 nm, respectively, were fixed on TiO2, and the Au/TiO2 sample exhibited strong photoabsorption around 550 nm due to surface plasmon resonance (SPR) of the larger Au particles. Various Au/TiO2 samples were prepared by changing the Au loading per photodeposition and the number of photodepositions. Effects of the conditions in MS photodeposition and sample calcination on Au particle distribution and photoabsorption properties were investigated. These samples were used for hydrogen (H2) formation from 2-propanol and mineralization of acetic acid in aqueous suspensions under irradiation of visible light. In the case of H2 formation under deaerated conditions, the reaction rate of Au/TiO2 having both larger and smaller particles was 4 times higher than that of the Au/TiO2 sample without smaller Au particles, indicating that smaller Au particles acted effectively as a co-catalyst, that is, as reduction sites for H2 evolution. On the other hand, in the case of mineralization of acetic acid under aerated conditions, carbon dioxide formation rates were independent of the presence of smaller Au particles, indicating that the smaller Au particles had little effect on the mineralization of acetic acid. To extend the possibility of Au/TiO2 for H2 formation under irradiation of visible light, H2 formation from ammonia (NH3) as biomass waste was examined under deaerated conditions; NH3 was decomposed to H 2 and nitrogen with a stoichiometric ratio of 3:1. The Royal Society of Chemistry 2014.

Autothermal reforming of CH4 over supported Ni catalysts prepared from Mg-Al hydrotalcite-like anionic clay

Takehira, Katsuomi,Shishido, Tetsuya,Wang, Peng,Kosaka, Tokuhisa,Takaki, Ken

, p. 43 - 54 (2004)

spc-Ni/MgAl (spc: solid-phase crystallization method) catalysts were prepared from Mg-Al hydrotalcite-like compounds containing Ni at the Mg site as the precursors and tested for partial oxidation of CH4 into synthesis gas. The activity of spc-

Structure of surface tantalate species and photo-oxidation of carbon monoxide over silica-supported tantalum oxide

Tanaka, Tsunehiro,Nojima, Hiroyuki,Yamamoto, Takashi,Takenaka, Sakae,Funabiki, Takuzo,Yoshida, Satohiro

, p. 5235 - 5239 (1999)

Tantalum oxide (10 wt.% as Ta2O5) supported on silica was prepared and the structure and the photo-oxidation of carbon monoxide over the catalyst sample were investigated. XAFS analysis showed that surface tantalate is a TaO4 tetrahedral species with a Ta=O bond which is a photoactive center. The initiation of the photo-oxidation of carbon monoxide is the photoadsorption of an oxygen molecule on the catalyst sample, elucidated by photoluminescence. EPR spectroscopy showed that the photo-excited center interacts with an oxygen molecule to form a T-type ozonide ion. A carbon monoxide ion attacks the ozonide ion to form an [O3-CO]- paramagnetic intermediate to lead the production of carbon dioxide.

Purification and characterization of urease from dehusked pigeonpea (Cajanus cajan L) seeds.

Das, Nilanjana,Kayastha, Arvind M,Srivastava, Punit K

, p. 513 - 521 (2002)

Urease has been purified from the dehusked seeds of pigeonpea (Cajanus cajan L.) to apparent electrophoretic homogeneity with approximately 200 fold purification, with a specific activity of 6.24 x10(3) U mg(-1) protein. The enzyme was purified by the sequence of steps, namely, first acetone fractionation, acid step, a second acetone fractionation followed by gel filtration and anion-exchange chromatographies. Single band was observed in both native- and SDS-PAGE. The molecular mass estimated for the native enzyme was 540 kDa whereas subunit values of 90 kDa were determined. Hence, urease is a hexamer of identical subunits. Nickel was observed in the purified enzyme from atomic absorption spectroscopy with approximately 2 nickel ions per enzyme subunit. Both jack bean and soybean ureases are serologically related to pigeonpea urease. The amino acid composition of pigeonpea urease shows high acidic amino acid content. The N-terminal sequence of pigeonpea urease, determined up to the 20th residue, was homologous to that of jack bean and soybean seed ureases. The optimum pH was 7.3 in the pH range 5.0-8.5. Pigeonpea urease shows K(m) for urea of 3.0+/-0.2 mM in 0.05 M Tris-acetate buffer, pH 7.3, at 37 degrees C. The turnover number, k(cat), was observed to be 6.2 x 10(4) s(-1) and k(cat)/K(m) was 2.1 x 10(7) M(-1) s(-1). Pigeonpea urease shows high specificity for its primary substrate urea.

Catalytic low-temperature combustion of dichloromethane over V-Ni/TiO2 catalyst

Zhang, Xinhua,Pei, Zhiying,Ning, Xingjie,Lu, Hanfeng,Huang, Haifeng

, p. 79192 - 79199 (2015)

Vanadium-nickel mixed oxides supported on TiO2 (anatase) were prepared by wet impregnation using ammonium metavanadate and nickel nitrate aqueous solution. The performance of as-prepared samples in catalytic dichloromethane (DCM) combustion was investigated, and their physicochemical properties were characterized in detail by X-ray diffraction, N2 physisorption, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, and Raman spectroscopy analyses. Results showed DCM combustion activity over V-Ni/TiO2 catalyst was superior to that of V2O5/TiO2 and NiO/TiO2 catalysts. DCM could be completely converted into CO2, HCl, and a little amount of CO over Ni-V/TiO2 catalyst at 350 °C, the toxic by-products, such as CH3Cl, aldehydes and phosgene could not be observed by online IR spectroscopy. The high catalytic activity, selectivity, and stability of V-Ni/TiO2 catalyst could be due to the good oxidative dehydrogenation ability (ODH), the good reducibility of active oxygen species, and suitable strength of Lewis acidic sites upon introduction of nickel oxide.

Polyethylene glycol-doped BiZn2VO6 as a high-efficiency solar-light-activated photocatalyst with substantial durability toward photodegradation of organic contaminations

Pirhashemi, Mahsa,Elhag, Sami,Habibi-Yangjeh, Aziz,Pozina, Galia,Willander, Magnus,Nur, Omer

, p. 37480 - 37491 (2018)

In this study, we focus on a simple, low-priced, and mild condition hydrothermal route to construct BiZn2VO6 nanocompounds (NCs) as a novel photocatalyst with strong solar light absorption ability for environmental purification using solar energy. NCs were further doped with polyethylene glycol (PEG) to improve their photocatalytic efficiency for photodegradation processes through inhibition of fast charge carrier recombination rates and higher charge separation efficiency. Surface morphology, phase structure, optical characteristics, and band structure of the as-prepared samples were analyzed using XRD, EDX, XPS, SEM, UV-vis spectroscopy, CL, and BET techniques. PEG-doped BiZn2VO6 NCs were applied as effective materials to degrade various kinds of organic pollutants including cationic and anionic types, and these NCs exhibited excellent photocatalytic efficiency as compared to traditional photocatalysts. In particular, the PEG-doped BiZn2VO6 (0.10% w/v) photocatalyst exhibited highly enhanced photocatalytic performance with improvements of about 46.4, 28.3, and 7.23 folds compared with PEG-doped ZnO nanorods (NRs), pristine BiVO4, and BiZn2VO6 samples, respectively, for the decomposition of congo red (CR) dye. After 40 minutes of sunlight irradiation, 97.4% of CR was decomposed. In this study, scavenging experiments indicated that both hydroxyl radicals and holes play dominant roles in CR photodegradation under simulated solar light irradiation. Meanwhile, the optimal photocatalyst demonstrated good reproducibility and stability for successive cycles of photocatalysis.

Highly efficient Pd-ZnO catalyst doubly promoted by CNTs and Sc 2O3 for methanol steam reforming

Yang, Lu,Lin, Guo-Dong,Zhang, Hong-Bin

, p. 137 - 144 (2013)

A type of Pd-ZnO catalyst doubly promoted by CNTs and Sc2O 3 for methanol steam reforming (MSR) was developed, and displayed excellent activity and operation stability for the selective formation of H 2 and CO2. Over a Pd0.15Zn1Sc 0.067-10%CNTs catalyst under the reaction conditions of 0.5 MPa and 548 K, the STY(H2) can maintain stable at the level of 1.56 mol h-1 g-1 at 75 h after the reaction started, which was 1.7 times that of the corresponding (CNTs and Sc)-free counterpart Pd 0.15Zn1. Characterization of the catalyst revealed that the highly conductive CNTs could promote hydrogen spillover from the PdZn/ZnO-sites to the CNTs adsorption-sites, and then combine to form H 2(a), followed by desorbing to H2(g), which would help increase the rate of a series of surface dehydrogenation reactions in the MSR process. The pronounced modification action of Sc3+ may be due to the high solubility of Sc2O3 in ZnO lattice. Solution of a small amount of Sc2O3 in ZnO lattice resulted in the formation of Schottky defects in the form of cationic vacancies at the surface of ZnO, where the (PdZn)0-Pd2+ clusters can be better stabilized through the Pd2+ accommodated at the surface vacant cation-sites. This would be conducive to inhibiting the sintering of the catalytically active (PdZn)0 nanoparticles, and thus, markedly prolonging the life of the catalyst.

Applebey, M. P.,Lane, K. W.

, p. 609 - 622 (1918)

Enhanced performance of chemical looping combustion of methane with Fe2O3/Al2O3/TiO2 oxygen carrier

Wu, Hsuan-Chih,Ku, Young

, p. 39902 - 39912 (2018)

Iron-based oxygen carriers supported on alumina or alumina/titania were prepared and evaluated for chemical looping combustion of methane. The reduction conversion of Fe2O3/Al2O3 and Fe2O3/Al2O3/TiO2 particles was markedly increased with increasing inlet concentration and was slightly enhanced by elevated operating temperatures. According to the shrinking core model, the mass transfer coefficients (kg) of Fe2O3/Al2O3 and Fe2O3/Al2O3/TiO2 reduction with methane are found to be 0.07 and 0.12?mm s?1. Complete combustion of methane is almost achieved for experiments conducted with Fe2O3/Al2O3 and Fe2O3/Al2O3/TiO2 operated as the Fe2O3/CH4 molar ratio reached about 5.4 and 4.4, respectively. Carbon deposition during methane combustion was avoided by using Fe2O3/Al2O3/TiO2 as an oxygen carrier. More heat was generated for the combustion of methane by Fe2O3/Al2O3/TiO2 oxygen carriers because methane more fully reacted with the Fe2O3 contained in the Fe2O3/Al2O3/TiO2 oxygen carriers.

Conversion of methyl lactate to acrylates over modified NaY zeolite catalysts

Takahashi, Atsushi,Shibasaki-Kitakawa, Naomi,Fujitani, Tadahiro

, p. 1581 - 1583 (2015)

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Photocatalytic degradation of acetic acid in the presence of visible light-active TiO2-reduced graphene oxide photocatalysts

Morawski,Kusiak-Nejman,Wanag,Kapica-Kozar,Wróbel,Ohtani,Aksienionek,Lipińska

, p. 108 - 113 (2017)

Visible light-active TiO2–reduced graphene oxide photocatalysts were prepared using simple mechanical mixing of titanium dioxide with different amounts of rGO (0.1, 0.5, 1.0 and 2.0?wt.%) in the presence of 1-butyl alcohol. Structures and morphologies of the samples were examined by means of FTIR/DRS, UV–vis/DR, XRD, SEM, TEM and Raman spectroscopy. The photocatalytic properties were checked on the basis of acetic acid photooxidation (the steady rate of linear increase of the CO2 yield was used for the estimation of photocatalytic activity). The maximum photodegradation rate was observed for TiO2 decorated with 0.5 wt.% of rGO. The enhancement of photodegradation efficiency should be related to π-conjugation system, two-dimensional planar structure and efficient charge separation of reduced graphene oxide nanosheets.

Surface reactivity and self-oscillating oxidation of butan-2-ol over palladium loaded AlPO4

Ouariach, Omar,Kacimi, Mohamed,Ziyad, Mahfoud

, p. 84 - 93 (2015)

Abstract Palladium loaded AlPO4 catalysts were synthesised and characterised by XRD, IR, UV-vis spectroscopy, temperature programmed desorption (TPD) and temperature programmed surface reaction (TPSR). The Pd2+ ions of the dispersed palladium on the amorphous surface of AlPO4 are in D4h symmetry. They can partially be reduced into Pd0 even in dynamic conditions by a mixture of butan-2-ol and oxygen. TPD/TPSR showed that the active sites are formed by the couple PdO/Pd. The presence of PdO on the surface favours the production of methyl ethyl ketone (MEK). The CO2 formation was never observed below 100 °C. Moreover, desorption of the MEK takes place in two waves arising from two different types of sites. Only the reactivity of the first set of sites which are located around 80 °C was considered in the present study. As a matter of fact, the oxidation of butan-2-ol into MEK (one) appear around 85 °C and stop before 100 °C. Oscillations of the temperature of the catalyst bed were also recorded but their amplitude never exceeds 7 °C. An oscillatory regime appears also for butan-2-ol pressures ranging from 0.61 to 1.65 kPa and for a total flow rate between 80 and 260 mL min-1. The oscillating oxidation of butan-2-ol is accompanied by a significant enhancement of the methyl ethyl ketone production.

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Langmuir, I.

, p. 2221 - 2295 (1916)

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Improving heterogeneous photo-Fenton catalytic degradation of toluene under visible light irradiation through Ba-doping in BiFeO3 nanoparticles

Soltani, Tayyebeh,Lee, Byeong-Kyu

, p. 199 - 207 (2016)

In this study, we prepared Bi1-xBaxFeO3 MNPs (x?=?0.03, 0.08, 0.12) via a rapid sol gel procedure to improve heterogeneous photo-Fenton catalytic degradation of toluene under visible light irradiation. We found that Ba-substitution in BiFeO3 magnetic nanoparticles (BFO MNPs) can play an important role in improving the photo-Fenton catalytic degradation of toluene from aqueous solution. Increasing the Ba doping level up to 12%, greatly affect in iron redox cycling and oxygens vacancies as compared to pure BFO MNPs. The iron redox cycling and existence of oxygen on the surface of Ba doped BFO had been affected by the photo-Fenton process. The scavenger effect evident from the study results confirmed that the photo-Fenton catalytic degradation of toluene from aqueous solution was mainly controlled by the formation characteristics of hydroxyl radical ([rad]OH) and also partially by the formation of other active species such singlet oxygen (1O2). The proposed radical reaction mechanism was also discussed. The degradation of toluene was partial in the dark but almost complete under visible light irradiation by the photo-Fenton catalytic degradation reaction. Bi1-x Bax FeO3 (x?=?0.12) showed the highest photo-Fenton catalytic degradation efficiency with a toluene removal of 98%, total organic carbon (TOC) and chemical oxygen demand (COD) reduction of 85% and 94%, respectively, after 40?min of visible light irradiation.

Effect of pressure on the phase composition of Li(Na)/W/Mn/SiO2 composites and their catalytic activity for oxidative coupling of methane

Nipan,Artukh,Yusupov,Loktev,Spesivtsev,Dedov,Moiseev

, p. 912 - 916 (2014)

The phase state of Li/W/Mn/SiO2 and Na/W/Mn/SiO2 composites after exposure to high pressures (2.5 GPa at 500°C) and subsequent exploitation in oxidative coupling of methane (OCM) was studied. Comparison of the catalytic activity of the composites before and after exposure to high pressures indicates that the formation of Li(Na)/W/Mn/SiO2 composites catalytically active for OCM is significantly influenced by high pressures.

Effects of Sodium Tetraborate as an Additive on the Reaction of α-Alumina with Sodium Carbonate

Chang, Byong-Tae,Oh, Jae-Gun,Om, Suk-Ja

, p. 1600 - 1604 (1980)

Effects of sodium tetraborate as an additive in the reaction of α-alumina with molten sodium carbonate have been studied mainly in a N2 atmosphere.Addition of sodium tetraborate accelerates the reaction, the α-alumina reacted increasing from 31.7percent to 99.3percent by addition of sodium tetraborate corresponding to the initial B2O3/Na2O molar ratio of only 1/15 under the other same conditions.By means of the Jander equation the activation energy was found to be 53 kcal/mol for the α-Al2O3-Na2CO3-Na2B4O7 system, which was lower by 10 kcal/mol than that for the α-Al2O3-Na2CO3 system.X-Ray diffraction and thermal data were analyzed in relation to the phase equilibrium of the melt.

Partial oxidation of methane to synthesis gas: Novel catalysts based on neodymium–calcium cobaltate–nickelate complex oxides

Dedov,Shlyakhtin,Loktev,Mazo,Malyshev,Tyumenova,Baranchikov,Moiseev

, p. 43 - 47 (2018)

Novel catalysts based on neodymium–calcium cobaltate–nickelate complex oxides for the partial oxidation of methane to synthesis gas have been synthesized and studied using catalyst precursors with the general formula NdCaCo1–xNixOn (x = 0, 0.2, 0.4, 0.6, 0.8, 1) prepared by the solid state synthesis method. It has been shown that the synthesized samples form a series of solid solutions with a K2NiF4 structure at x ≤ 0.8 or a rhombically distorted K2NiF4 structure at x = 1. The products of conversion of the resulting precursors in a methane–oxygen mixture at high temperatures have shown high methane conversions and synthesis gas yields. The highest values of these parameters have been achieved in the presence of catalysts synthesized by the reduction of NdCaCo0.4Ni0.6On and NdCaNiOn precursors. The complete replacement of cobalt with nickel has led to an increase in the synthesis gas yield; however, it has been found that the resulting catalyst is prone to carbonization. It has been determined that an optimum nickel to cobalt ratio in the catalyst composition provides the formation of a carbonization-resistant catalyst.

Highly-efficient steam reforming of methanol over copper modified molybdenum carbide

Ma, Yufei,Guan, Guoqing,Hao, Xiaogang,Zuo, Zhijun,Huang, Wei,Phanthong, Patchiya,Kusakabe, Katsuki,Abudula, Abuliti

, p. 44175 - 44184 (2014)

Cu doped molybdenum carbide (Cu-MoxCy) catalysts were prepared by carburization of Cu doped molybdenum oxide (Cu-MoO3) using a temperature-programmed reaction with a 20% CH4-H2 mixture at 700 °C. Phas

FOx News: Towards Methanol-driven Biocatalytic Oxyfunctionalisation Reactions

Willot, Sébastien J.-P.,Hoang, Manh Dat,Paul, Caroline E.,Alcalde, Miguel,Arends, Isabel W. C. E.,Bommarius, Andreas S.,Bommarius, Bettina,Hollmann, Frank

, p. 2713 - 2716 (2020)

The novel formate oxidase from Aspergillus oryzae (AoFOx) is a useful catalyst to promote H2O2-dependent oxyfunctionalisation reactions. In this contribution we exploit the substrate promiscuity of AoFOx to fully oxidise methanol and formaldehyde to CO2 and drive peroxygenase-catalysed stereoselective oxyfunctionalisation reactions. The highly atom efficient H2O2 generation system also enabled high catalytic turnover of the peroxygenase production enzyme.

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Balarew, D.,Lukowa, N.

, p. 222 - 227 (1930)

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Enhanced formic acid electro-oxidation on pdir nanoparticles prepared by ethylene glycol-assisted NaBH4 reduction process

Chen, Jinwei,Wang, Gang,Wang, Xueqin,Tian, Jing,Zhu, Shifu,Wang, Ruilin

, p. 7008 - 7011 (2013)

The carbon supported PdIr nanoparticles were synthesized by an ethylene glycol-assisted NaBH4 reduction method, and the mass ratio of Pd to Ir was optimized. Then, their performances for formic acid electro-oxidation (FAEO) were investigated. The XRD and

Toluene oxidation catalyzed by NiO/SiO2 and NiO/TiO2/SiO2: Towards development of humidity-resistant catalysts

Park, Eun Ji,Lee, Ju Ha,Kim, Kwang-Dae,Kim, Dae Han,Jeong, Myung-Geun,Kim, Young Dok

, p. 100 - 106 (2016)

Toluene oxidation was catalyzed by NiO/SiO2 and NiO/TiO2/SiO2 under dry and highly humid (relative humidity = 70%) conditions at 250 and 350 °C. At 350 °C, both catalysts showed nearly complete removal of toluene and conversion of toluene to CO2 under humid as well as dry conditions. Catalytic activity of the NiO/SiO2 was significantly decreased by the increase in the humidity at 250 °C, whereas that of NiO/TiO2/SiO2 was much less sensitive to the humidity. A facile adsorption of water on NiO/SiO2 due to the hydrophilic nature of SiO2 surface resulted in a pronounced suppression of toluene adsorption on the surface and lower catalytic activity under humid conditions. On the contrary, a higher affinity of TiO2 towards toluene adsorption even under highly humid conditions can allow more humidity-independent catalytic activity of NiO/TiO2/SiO2. We suggest that the modulation of surface structure of supporting materials of nanoparticle catalysts can be useful for fabrication of more humidity-resistant heterogeneous catalysts.

Effects of la doping on structural, optical, electronic properties of Sr2Bi2O5 photocatalyst

Obukuro, Yuki,Matsushima, Shigenori,Obata, Kenji,Suzuki, Takuya,Arai, Masao,Asato, Eiji,Okuyama, Yuji,Matsunaga, Naoki,Sakai, Go

, p. 139 - 146 (2016)

Single-phase Sr2Bi2O5 was obtained by calcination of the heterobimetallic complex precursor Sr[Bi(DTPA)]·9H2O (DTPA is diethylenetriaminepentaacetic acid) at 700 °C for 6 h. The effect of La doping on the crystal structure, surface area, morphology, surface chemical state, and absorption properties of Sr2Bi2O5 samples prepared from Sr[Bi(DTPA)]·9H2O were investigated. No traces of an impurity phase were detected in samples with a lower La content (3 and 5 mol%), while impurity phases such as Sr6Bi2O9 and SrCO3 were observed in Sr2Bi2O5 samples with larger La contents of 8 and 10 mol%. The Brunauer-Emmett-Teller surface area of Sr2Bi2O5 increased slightly with the content of La. High-resolution transmission electron microscopy revealed clear crystalline planes for both undoped and La-doped Sr2Bi2O5 samples without amorphous phases. Meanwhile, X-ray photoelectron spectroscopy indicated that the valence states of constituent metals were Sr2+, Bi3+, and La3+. The solubility limit of La in the Sr2Bi2O5 crystal phase was determined from Raman scattering measurements. La atoms substituted Bi sites when the doping content was low, while both Bi and Sr sites were substituted with La when the content of La was high. The electronic structure of Sr2Bi2O5 could be modified by La doping, resulting in a red shift of the absorption edge with increasing La content. The band-gap narrowing of Sr2Bi2O5 with La-doping was reproduced in energy-band calculations. The photocatalytic activity of Sr2Bi2O5 under visible-light irradiation for the oxidation of isopropanol was enhanced by doping with La.

Effects of metal promotion on the performance of CuZnAl catalysts for alcohol synthesis

Beiramar, Jorge M.,Griboval-Constant, Anne,Khodakov, Andrei Y.

, p. 1788 - 1793 (2014)

A series of CuZnAl catalysts modified with different promoters (Fe, Co, Ru, Zr, Mo, Mg, Mn, and Cr) have been prepared through co-precipitation, characterised by applying a combination of techniques, and tested for carbon monoxide hydrogenation. Cu reducibility in CuZnAl catalysts was affected by the addition of promoters. The ease of Cu reduction in the promoted catalysts leads to more active catalysts for the hydrogenation of carbon monoxide and the production of C2+ alcohols, whereas lower catalytic activity was observed over less reducible catalysts. The promotion of CuZnAl catalysts even with small amounts of Cr, Mn, and Fe resulted in a significant modification in the reaction selectivity. The Fe-containing catalyst demonstrated a dramatic increase in carbon monoxide conversion and C2+ alcohol productivity (30 mg g-1cath-1). Choose your alcohol wisely: The ease of Cu reduction in CuZnAl methanol synthesis catalysts promoted with metals leads to more active catalysts for the hydrogenation of carbon monoxide and the production of C2+ alcohols. The promotion of CuZnAl catalysts even with small amounts of Cr, Mn, and Fe results in a significant modification in the selectivity patterns.

Effect of active and inert oxide on catalytic partial oxidation (CPO) of methane over supported Ni catalysts

LaParola, V.,Pantaleo, G.,Venezia, Anna

, (2021/11/27)

The effects of preparation method, types of carrier and different catalyst and support structures on the CH4 catalytic partial oxidation (CPO) activity of supported Ni catalysts are reviewed with respect to selected results obtained by this research group during the last five years. In particular, different preparation methods and structural effect of Ni supported on La2O3, on CeO2 and on mixed CeO2-La2O3 are discussed. The effects of the peculiarity of an active (redox) and of an inert oxide carrier, influencing the metal dispersion, the metal reducibility and the carbon formation, are considered by comparing the catalytic performance of nickel catalysts supported on CeO2 and on SiO2. Ni supported over a high surface area silica will be compared with a corresponding ceria-doped nickel catalyst. The results of a detailed material characterization attained by several techniques as XPS, XRD, TPR/TPO are described, aiming to elucidate the structure - activity relationship. The reviewing of the different case studies illustrates the importance of the interaction between support and active metals ultimately determining the surface distribution of the active sites and their final catalytic activity.

Rapid alloying of Au–Pd nanospheres by a facile pulsed laser technique: Insights into a molar-dependent electrocatalytic methanol oxidation reaction

Chinnadurai, Deviprasath,Choi, Myong Yong,Lee, Seung Jun,Lee, Young Wook,Yeon, Sanghun,Yu, Yiseul

, (2021/10/04)

Direct methanol fuel cells have attracted extensive research interest because of their relatively high energy density and portability. It is important to rationally design the composition and surface atomic structure by efficient synthesis protocols to boost cell efficiency. In this study, we employed cohesive pulsed laser irradiation and ultrasonochemical techniques to synthesize and tune the molar ratio of an Au–Pd alloy for the methanol oxidation reaction (MOR). The effective implementation of extremely rapid photoinduced reduction and reaction conditions resulted in the formation of well-dispersed and homogenous nanospheres of the Au–Pd alloy with uniform particle size. Moreover, the composition-tuned Au–Pd alloy exhibited an improved electrocatalytic activity, which might be due to its improved electrical conductivity and higher CO tolerance. The alloy achieved relatively high mass and specific activities of 0.50 A/mgPd and 1.36 mA/cmPd2, respectively. Additionally, we studied the effect of the Au–Pd composition on the MOR activity and analyzed the reaction kinetics in depth. This work provides the foundation for implementing a laser-based technique to synthesize Pd-based alloy electrocatalysts for MOR application.

Mesoporous Co3O4 with large specific surface area derived from MCM-48 for catalytic oxidation of toluene

Gao, Wei,Tang, Xiaolong,Xie, Xizhou,Yi, Honghong,Yu, Qingjun,Zhang, Yuanyuan,Zhuang, Ruijie

, (2021/12/30)

As one of the most promising candidates for the catalytic combustion of volatile organic compounds, crystalline cobalt oxide is one of the most used and cost-effective catalyst. We present here a mesoporous Co3O4 catalyst with large specific surface area of 182.5 ?m2/g derived from MCM-48 with a specific surface area of 1470.9 ?m2/g, giving the T90 (the temperature required for achieving a toluene conversion of 90%) of 229 ?°C and the apparent activation energy (Ea) of 17.53 ?kJ/mol for the oxidation of toluene, both of which are much lower than the Co3O4 catalysts prepared by using SBA-15 and MCM-41 as hard template (T90 ?~ ?260 ?°C, Ea ?~ ?30 ?kJ/mol). Constant complete conversion of toluene over M48-Co3O4 was observed for 60 ?h, suggesting its superior stability for toluene combustion. Characterization results indicated the large specific surface area, higher Co3+/Co2+ ratio as well as abundant surface-active oxygen exposed for easy accessibility of reactant molecules contribute simultaneously to the good catalytic oxidation performance of M48-Co3O4. Particularly, 400 ?°C was viewed to be the optimal calcination temperature for keeping the mesoporous structures of catalyst as much as possible. The reaction intermediates of toluene oxidation over M48-Co3O4 were detected based on both GC-MS and in-situ DRIFTS, demonstrating the formation of the benzyl alcohol, benzaldehyde, benzoic acid, itaconic anhydride and maleic anhydride, acetone, and acetic acid, etc., as the main intermediates.