The steam reforming of phenol reaction over supported-Rh catalysts

Abstract The steam reforming of phenol reaction towards H 2 production was studied in the 575–730 °C range over Rh supported on CeO 2 , ZrO 2 and SiO 2 single metal oxides and various mixed metal oxides such as CeO 2 –SiO 2 , ZrO 2 –SiO 2 and CeO 2 –ZrO 2 . The effect of synthesis method (wet impregnation versus sol–gel) of the mixed metal oxide used as support of Rh on the activity and selectivity of reaction towards hydrogen formation has also been investigated. It was found that the 1.5 wt.% Rh/Ce–Zr–O catalyst, the support of which was prepared by the sol–gel method, exhibits better performance than a commercial Ni-based catalyst both solids examined under the same experimental conditions. The 1.5 wt.% Rh/Ce–Zr–O catalyst presented practically constant hydrogen product concentration (∼10 mol%) in the 575–730 °C range and after using a 0.5% C 6 H 5 OH/40% H 2 O/He feed gas mixture at a space velocity of 80.000 h −1 , to be compared to 8–9.5 mol% H 2 obtained over the commercial Ni-based catalyst. This particular supported-Rh catalyst showed also no more than 18% drop in activity after 24 h of continuous reaction. The effect of Rh loading (0.5 and 1.5 wt.%) on catalyst activity towards H 2 production was studied over Rh supported on CeO 2 and ZrO 2 . It was found that the steam reforming of phenol reaction is favored over catalysts with small Rh particles. The effect of the partial pressure of water and phenol in the reaction feed stream on catalyst activity towards hydrogen was found to strongly depend on catalyst support chemical composition and reaction temperature. Increasing the water concentration in the 20–40 mol% range resulted in a significant increase of H 2 product yield. A similar result was also obtained in the case of phenol in the 0.3–0.5 mol% range. The accumulation of carbonaceous deposits during reaction conditions was investigated by temperature-programmed oxidation (TPO) and transient isothermal reaction with steam experiments following reaction. More than one kind of carbonaceous species have been identified with varying composition and reactivity towards oxygen and steam.

[1]  D. Duprez,et al.  Hydrogen formation in the reaction of steam with Rh/CeO2 catalysts: a tool for characterising reduced centres of ceria , 2003 .

[2]  B. Kelleher,et al.  Review of literature on catalysts for biomass gasification , 2001 .

[3]  J. Fierro,et al.  New catalytic routes for syngas and hydrogen production , 1996 .

[4]  J. Rostrup-Nielsen,et al.  Promotion of Steam Reforming Catalysts , 1998 .

[5]  J. Armor,et al.  The multiple roles for catalysis in the production of H2 , 1999 .

[6]  D. Grenoble.  The chemistry and catalysis of the water/toluene reaction: 2. The role of support and kinetic analysis , 1978 .

[7]  D. Duprez,et al.  Steam dealkylation of aromatic hydrocarbons: II. Role of the support and kinetic pathway of oxygenated species in toluene steam dealkylation over group VIII metal catalysts , 1982 .

[8]  Pekka Simell,et al.  Catalytic purification of tarry fuel gas , 1990 .

[9]  V. Choudhary,et al.  A method for increasing the surface area of perovskite-type oxides , 2000 .

[10]  J. Rostrup-Nielsen,et al.  Innovation and science in the process industry: Steam reforming and hydrogenolysis , 1999 .

[11]  T. Salmi,et al.  A dynamic study of the water-gas shift reaction over an industrial ferrochrome catalyst , 1988 .

[12]  Daniel Montané,et al.  Steam reforming model compounds of biomass gasification tars: conversion at different operating conditions and tendency towards coke formation , 2001 .

[13]  Dezheng Wang,et al.  OH spillover from a γ-Al2O3 support in the partial oxidation of methane over Ru/Al2O3 , 2003 .

[14]  V. Choudhary,et al.  Activation by hydrothermal treatment of low surface area ABO3-type perovskite oxide catalysts , 2000 .

[15]  Daniel Duprez,et al.  Selective steam reforming of aromatic compounds on metal catalysts , 1992 .

[16]  F. Solymosi.  Importance of the Electric Properties of Supports in the Carrier Effect , 1968 .

[17]  Mohammad Asadullah,et al.  A novel catalytic process for cellulose gasification to synthesis gas , 2001 .

[18]  Mohammad Asadullah,et al.  Biomass Gasification to Hydrogen and Syngas at Low Temperature: Novel Catalytic System Using Fluidized-Bed Reactor , 2002 .

[19]  J. Fierro,et al.  Methane combustion on Rh/ZrO2 catalysts , 1998 .

[20]  J. Kašpar,et al.  Modification of the Redox Behaviour of CeO2Induced by Structural Doping with ZrO2 , 1996 .

[21]  Jesús Arauzo,et al.  Catalytic pyrolysis of biomass: influence of the catalyst pretreatment on gas yields , 2001 .

[22]  X. Verykios,et al.  Charge Transfer in Metal Catalysts Supported on Doped TiO2: A Theoretical Approach Based on Metal–Semiconductor Contact Theory , 1996 .

[23]  John L. Falconer,et al.  Spillover in Heterogeneous Catalysis , 1995 .

[24]  J. Ross,et al.  Evidence for the participation of surface nickel aluminate sites in the steam reforming of methane over nickel/alumina catalysts , 1978 .

[25]  J. Pintado,et al.  Image simulation and experimental HREM study of the metal dispersion in Rh/CeO2 catalysts. Influence of the reduction/reoxidation conditions , 1998 .

[26]  D. L Trimm,et al.  Catalysts for the control of coking during steam reforming , 1999 .

[27]  J. Kašpar,et al.  Effect of ZrO2 content on textural and structural properties of CeO2–ZrO2 solid solutions made by citrate complexation route , 2003 .

[28]  Raymond J. Gorte,et al.  A comparative study of water-gas-shift reaction over ceria supported metallic catalysts , 2001 .

[29]  R. Gorte,et al.  A study of steam reforming of hydrocarbon fuels on Pd/ceria , 2002 .

[30]  Mauro Graziani,et al.  Rh-Loaded CeO2-ZrO2 Solid-Solutions as Highly Efficient Oxygen Exchangers: Dependence of the Reduction Behavior and the Oxygen Storage Capacity on the Structural-Properties , 1995 .

[31]  D. Świerczyński,et al.  Hydrogen production from biomass gasification on nickel catalysts: Tests for dry reforming of methane , 2002 .

[32]  C. Costa,et al.  The Selective Catalytic Reduction of Nitric Oxide with Methane over La2O3–CaO Systems: Synergistic Effects and Surface Reactivity Studies of NO, CH4, O2, and CO2 by Transient Techniques , 2000 .

[33]  Wang Yanhui,et al.  The experimental research for production of hydrogen from n-octane through partially oxidizing and steam reforming method , 2001 .

[34]  Mohammad Asadullah,et al.  Demonstration of real biomass gasification drastically promoted by effective catalyst , 2003 .

[35]  Daniel Montané,et al.  Biomass to hydrogen via fast pyrolysis and catalytic steam reforming of the pyrolysis oil or its fractions , 1996 .

[36]  Lucía García,et al.  Catalytic steam reforming of bio-oils for the production of hydrogen : effects of catalyst composition , 2000 .

[37]  A. Heinzel,et al.  Reforming of natural gas—hydrogen generation for small scale stationary fuel cell systems , 2002 .

[38]  Carla E. Hori,et al.  Thermal stability of oxygen storage properties in a mixed CeO2-ZrO2 system , 1998 .

[39]  D. Bianchi,et al.  A Transient Kinetic Study of the Co/H2 Reaction on Rh/Al2O3 Using FTIR and Mass Spectroscopy , 1994 .

[40]  R. Gorte,et al.  The effect of Fe and other promoters on the activity of Pd/ceria for the water-gas shift reaction , 2003 .

[41]  J. Anderson,et al.  Introduction to Characterization and Testing of Catalysts , 1986 .