Ni catalyst on mixed support of CeO2-ZrO2 and Al2O3: Effect of composition of CeO2-ZrO2 solid solution on the methane steam reforming reaction

In this study, catalysts containing 5 wt.% Ni deposited on a support composed of a CeO2-ZrO2 solid solution deposited on alumina were tested in the steam reforming of methane. The supports, with various ratios of Ce to Zr, were prepared by co-precipitation of the oxide precursors, followed by calcination in synthetic air. The catalysts were then prepared by Ni impregnation of the supports. The prepared solids were characterized by temperature-programmed reduction with H-2 (TPR-H-2), in situ X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES) spectroscopy. The XRD analysis confirmed the formation of a solid solution between ZrO2 and CeO2. In the catalytic tests, it was found that catalysts with higher Ce content did not exhibit deactivation during 6 h of reaction. The catalyst with highest Ce content, Ni(0.8Ce0.2Zr)AI, provided the best result, with the highest rate of conversion of methane and the lowest carbon deposition, which may be partly due to the smaller Ni-0 crystallites in this sample and also the segregated CeO2 particles may have favored H2O adsorption which could lead to higher C gasification. (C) 2012 Elsevier B.V. All rights reserved.

Reforming dell'etanolo con processo ciclico: studio della reattività di ossidi misti con struttura spinello

This work deals with a study on the feasibility of a new process, aimed at the production of hydrogen from water and ethanol (a compound obtained starting from biomasses), with inherent separation of hydrogen from C-containing products. The strategy of the process includes a first step, during which a metal oxide is contacted with ethanol at high temperature; during this step, the metal oxide is reduced and the corresponding metallic form develops. During the second step, the reduced metal compound is contacted at high temperature with water, to produce molecular hydrogen and with formation of the original metal oxide. In overall, the combination of the two steps within the cycle process corresponds to ethanol reforming, where however COx and H2 are produced separately. Various mixed metal oxides were used as electrons and ionic oxygen carriers, all of them being characterized by the spinel structure typical of M-modified non-stoichiometric ferrites: M0,6Fe2,4O4 (M = Co, Mn or Co/Mn). The first step was investigated in depth; it was found that besides the generation of the expected CO, CO2 and H2O, the products of ethanol anaerobic oxidation, also a large amount of H2 and coke were produced. The latter is highly undesired, since it affects the second step, during which water is fed over the pre-reduced spinel at high temperature. The behavior of the different spinels was affected by the nature of the divalent metal cation. The new materials were tested in terms of both redox proprieties and catalytic activity to generate hydrogen. Still the problem of coke formation remains the greater challenge to solve.

NICKEL-COBALT SOLID SOLUTION AND ITS APPLICATIONS AS CATALYSTS FOR CARBON DIOXIDE REFORMING OF METHANE

Global warming issue becomes more significant to human beings and other organisms on the earth. Among many greenhouse gases, carbon dioxide (CO2) has the largest contribution to global warming. To find an effective way to utilize the greenhouse gas is urgent. It is the best way to convert CO2 to useful compounds. CO2 reforming of methane is an attractive process to convert CO2 and methane into synthesis gas (CO/H2), which can be used as a feedstock for gasoline, methanol, and other hydrocarbons. Nickel and cobalt were found to have good activity for CO2 reforming. However, they have a poor stability due to carbon deposition. This research developed efficient Ni-Co solid solution catalysts with excellent activities and high stability for CO2 reforming of methane. First, the structure of binary oxide solid solution of nickel and cobalt was investigated. It was found that while the calcination of Ni(NO3)2 and Co(NO3)2 mixture with 1:1 molar ratio at a high temperature above 800 oC generated NiO-CoO solid solution, only Ni3O4-Co3O4 solid solution was observed after the calcination at a low temperature of 500 oC. Furthermore, if the calcination was carried out at a medium temperature arranged from 600 to 700 oC, both NiO-CoO and Ni3O4-Co3O4 solid solutions can be formed. This occurred because Co3O4 can induce the formation of Ni3O4, whereas NiO can stabilize CoO. In addition, the lattice parameter of Ni3O4, which was predicted by using Vegard’s Law, is 8.2054 Å. As a very important part of this dissertation, Ni-Co solid solution was evaluated as catalysts for CO2 reforming of methane. It was revealed that nickel-cobalt solid solution showed excellent catalytic performance and high stability for CO2 reforming of methane. However, the stability of Ni-Co solid solution catalysts is strongly dependent on their composition and preparation condition. The optimum composition is 50%Ni-50%Co. Furthermore, the structure of Ni-Co catalysts was characterized by XRD, Vvis, TPR, TPD, BET, AES, TEM, XANES and EXAFS. The relationship between the structure and the catalytic performance was established: (1) The reduced NiO-CoO solid solution possesses better catalytic performance and stability than the reduced Ni3O4-Co3O4 solid solution. (2) Ni is richer on surface in Ni-Co catalysts. And (3) the reduction of Ni-Co-O solid solution generated two types of particles, small and large particles. The small ones are dispersed on large ones as catalytic component.

Methane dry reforming over Ni supported on pine sawdust activated carbon: Effects of support surface properties and metal loading

The influence of metal loading and support surface functional groups (SFG) on methane dry reforming (MDR) over Ni catalysts supported on pine-sawdust derived activated carbon were studied. Using pine sawdust as the catalyst support precursor, the smallest variety and lowest concentration of SFG led to best Ni dispersion and highest catalytic activity, which increased with Ni loading up to 3 Ni atoms nm-2. At higher Ni loading, the formation of large metal aggregates was observed, consistent with a lower "apparen" surface area and a decrease in catalytic activity. The H2/CO ratio rose with increasing reaction temperature, indicating that increasingly important side reactions were taking place in addition to MDR.

Zr-Laponite pillared clay-based nickel catalysts for methane reforming with carbon dioxide

Zr-Laponite pillared clays were prepared and used as supports of nickel catalysts for the methane reforming reaction with carbon dioxide to synthesis gas. The structural and textural characteristics of supports and catalysts were systematically examined by N-2 adsorption/desorption and X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron spectroscopy (TEM) techniques. The catalytic performance and carbon deposition were investigated. It is found that Zr-Laponite pillared clays are promising catalyst supports for carbon dioxide reforming of methane. The pore structure and surface properties of such supports greatly affect the catalytic behaviors of catalysts derived. Carbon deposition on catalysts was also affected by the property and structure of supports. The sintering of nickel metal and zirconia was another factor responsible for catalyst deactivation. This new-type nickel supported catalyst Ni/Zr-Laponite(8), with well-developed porosity, gave a higher initial conversion and a relatively long-term stability, and is therefore a promising catalyst for potential application to carbon dioxide reforming of methane to synthesis gas. (C) 2002 Elsevier Science B.V All rights reserved.

The steam reforming of hydrocarbons with special reference to methane

From an examination of the literature relating to the catalytic steam reforming of hydrocarbons, it is concluded that the kinetics of high pressure reforming, particularly steam-methane reforming, has received relatively little attention. Therefore because of the increasing availability of natural gas in the U.K., this system was considered worthy of investigation. An examination of the thermodynamics relating to the equilibria of steam-hydrocarbon reforming is described. The reactions most likely to have influence over the process are established and from these a computer program was written to calculate equilibrium compositions. A means of presenting such data in a graphica1 form for ranges of the operating variables is given, and also an operating chart which may be used to quickly check feed ratios employed on a working naphtha reforming plant is presented. For the experimental kinetic study of the steam-methane system, cylindrical pellets of ICI 46-1 nickel catalyst were used in the form of a rod catalyst. The reactor was of the integral type and a description is given with the operating procedures and analytical method used. The experimental work was divided into two parts, qualitative and quantitative. In the qualitative study the various reaction steps are examined in order to establish which one is rate controlling. It is concluded that the effects of film diffusion resistance within the conditions employed are negligible. In the quantitative study it was found that at 250 psig and 6500C the steam-methane reaction is much slower than the CO shift reaction and is rate controlling. Two rate mechanisms and accompanying kinetic rate equations are derived, both of which represent 'chemical' steps in the reaction and are considered of equal merit. However the possibility of a dual control involving 'chemical' and pore diffusion resistances is also expressed.

Catalytic supercritical water gasification of plastics with supported RuO2:a potential solution to hydrocarbons-water pollution problem

Here we report on a potential catalytic process for efficient clean-up of plastic pollution in waters, such as the Great Pacific Garbage Patch (CPGP). Detailed catalytic mechanisms of RuO2 during supercritical water gasification of common polyolefin plastics including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PP), have been investigated in a batch reactor at 450 °C, 60 min. All four plastics gave very high carbon gasification efficiencies (CGE) and hydrogen gasification efficiencies (HGE). Methane was the highest gas component, with a yield of up to 37 mol kg−1LDPE using the 20 wt% RuO2 catalyst. Evaluation of the gas yields, CGE and HGE revealed that the conversion of PS involved thermal degradation, steam reforming and methanation; whereas hydrogenolysis was a possible additional mechanism during the conversion of aliphatic plastics. The process has the benefits of producing a clean-pressurized methane-rich fuel gas as well as cleaning up hydrocarbons-polluted waters.

Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst:new insights into RuO2 catalytic reaction mechanisms

Five samples including a composite refuse derived fuel (RDF) and four combustible components of municipal solid wastes (MSW) have been reacted under supercritical water conditions in a batch reactor. The reactions have been carried out at 450 °C for 60 min reaction time, with or without 20 wt% RuO2/gamma-alumina catalyst. The reactivities of the samples depended on their compositions; with the plastic-rich samples, RDF and mixed waste plastics (MWP), giving similar product yields and compositions, while the biogenic samples including mixed waste wood (MWW) and textile waste (TXT) also gave similar reaction products. The use of the heterogeneous ruthenium-based catalyst gave carbon gasification efficiencies (CGE) of up to 99 wt%, which was up by at least 83% compared to the non-catalytic tests. In the presence of RuO2 catalyst, methane, hydrogen and carbon dioxide became the dominant gas products for all five samples. The higher heating values (HHV) of the gas products increased at least two-fold in the presence of the catalyst compared to non-catalytic tests. Results show that the ruthenium-based catalyst was active in feedstock steam reforming, methanation and possible direct hydrogenolysis of C-C bonds. This work provides new insights into the catalytic mechanisms of RuO2 during SCWG of carbonaceous materials, along with the possibility of producing high yields of methane from MSW fractions.

Chemical Loop Reforming dell'etanolo: studio della reattività di ferriti modificate

Modified ferrites with a generic formula of MFe2O4 (where M=Co, Cu, Mn and their combination: Cu/Co, Cu/Mn and Co/Mn) were studied as potentially attractive ionic oxygen and electron carrier materials for the production of “clean H2” via the Chemical Loop Reforming (CLR) of bio-ethanol. The conventional CLR process consists of 2 steps: 1st - the reduction step with ethanol; 2nd - the re-oxidation step with water. The synthesized materials were tested in a laboratory plant in terms of both redox properties and catalytic activity to generate hydrogen during the re-oxidation step with water steam over previously pre-reduced samples. The obtained results showed that CuFe2O4, Cu0.5Co0.5Fe2O4, Cu0.5Mn0.5Fe2O4 and CoFe2O4 within 20 min of ethanol reduction reached almost a complete reduction, and, as a consequence, the higher yields to H2 produced during the re-oxidation step with steam. On the other hand, incorporation of Mn-cations greatly affects the redox properties of a resulted spinel (MnFe2O4 and Co0.5Mn0.5Fe2O4) leading to its lower reducibility, caused by the formation of a hardly reducible layer of MnxFeyO oxide. Moreover, the presence of Mn-cations effectively reduces the amount of coke formed during the anaerobic reduction step with ethanol and hence avoids a fast deactivation of the material. Modification of the conventional CLR process with an addition of the 3rd regeneration step (carried out with air) was done in order to increase the stability of the looping material and to overcome the deactivation problems, such as: a coke deposition/accumulation and an incomplete re-oxidation of M0 during the 2nd step.

Bimetallic PtSn/C catalysts obtained via SOMC/M for glycerol steam reforming

A detailed study on the preparation of bimetallic PtSn/C catalysts using surface-controlled synthesis methods, and on their catalytic performance in the glycerol steam reforming reaction has been carried out. In order to obtain these well-defined bimetallic phases, techniques derived from Surface Organometallic Chemistry on Metals (SOMC/M) were used. The preparation process involved the reaction between an organometallic compound ((C4H9)4Sn) and a supported transition metal (Pt) in a H2 atmosphere. Catalysts with Sn/Pt atomic ratios of 0.2, 0.3, 0.5, and 0.7 were obtained, and characterized using several techniques: ICP, H2 chemisorption, TEM and XPS. These systems were tested in the glycerol steam reforming varying the reaction conditions (glycerol concentration and reaction temperature). The best performance was observed for the catalysts with the lowest tin contents (PtSn0.2/C and PtSn0.3/C). It was observed that the presence of tin increased the catalysts’ stability when working under more severe reaction conditions.

Encouraging ethics and challenging corruption : reforming governance in public institutions

Encouraging Ethics and Preventing Corruption brings theory and practice together in addressing the question: How are we to be ethical in public life and through public institutions? It is a major contribution to public sector ethics within Australia and internationally because it provides an exhaustive analysis of reform across a decade in one jurisdiction, Queensland, and then proceeds to itemise a best practice integrity system or ethics regime. Drawing on the extensive research of two of Australia's leading practical ethicists, this text is essential reading for all students and practitioners of applied and professional ethics in the public sphere. Part A of the text provides a preferred theoretical and conceptual framework which both justifies and guides the development of a public sector ethics regime. Part B examines the place of the individual within a world of institutional ethics. Part C outlines the Queensland governance reforms introduced since 1989 following the Fitzgerald Inquiry which exposed corruption in the police and ministry. The final chapter, the 'Epilogue', gathers the insights of earlier chapters and suggests a more explicitly ethics-centred approach to governance reform that may take us 'beyond best practice'. Clearly, while it is the Australian context we have in mind, we are confident that this is a text which addresses the quest for integrity and ethics in government wherever society is committed to social and liberal democratic ideals.

Embedding university perspectives in university teaching and learning : lessons learnt and possibilities for reforming/decolonising curriculum

Embedding Indigenous knowledge in the curriculum continues to challenge traditional western perspectives on Indigenous epistemologies and cultures. This paper will initially discuss experiences of embedding Indigenous perspectives in the curriculum at an Australian university. The project was inspired by the Reconciliation Statement which ensured funding through Teaching and Learning Large Grants. Its successful outcomes included the creation of identified positions for Indigenous academics within faculties, creation of a resource hub of relevant teaching materials and consistent documentation and awareness of Indigenous perspectives through interviews and workshops. The paper concludes by critically interrogating the methodology used to conceptualise Indigenous knowledge in embedding Indigenous perspectives in a university curriculum. This paper argues for a thorough curriculum reform if a degree of decolonisation of the western constructed Indigenous knowledge and its living systems are desired.