Effect Of Support Composition Research Articles

Ammonia synthesis using Co catalysts supported on MgO–Nd2O3 mixed oxide systems: Effect of support composition

This study presents the use of emerging support materials based on mixed magnesium–neodymium oxides for the dispersion of the Co metal for ammonia synthesis. A series of cobalt catalysts using mixed MgO–Nd2O3 oxide supports with different Mg/Nd molar ratios (2, 4, 7, 10, and 12) was successfully prepared. The N2 physisorption, XRD, HR-TEM, STEM-EDX, TPR/TG-MS, H2-TPD, and CO2-TPD studies of these systems revealed a strong correlation between the composition of the support and the overall catalyst performance. It was found that varying the Mg/Nd molar ratio caused a gradual change in the textural, structural and adsorption properties. The difference in the activity of the Co/MgO–Nd2O3 catalysts towards ammonia synthesis was mainly attributed to the different surface adsorption properties. The highest number of basic sites on the catalyst surface was noted for the support with the Mg/Nd molar ratio of 10. Also, the highest Co dispersion was obtained on this support, leading to the best distribution of Co particles with the smallest Co particle size. As a result, the Co/10MgO–Nd2O3 catalyst demonstrated superior activity for ammonia synthesis compared to other catalysts. The use of a binary composite support consisting of MgO and Nd2O3 with the properly selected ratio of each component is beneficial in terms of catalyst activity, stability and cost compared to single-oxide supports.

Synthesis of Methanol from СО2 on Cu–Zn/xAl2O3–(1 – x)SiO2 Catalysts. Effect of Support Composition

Synthesis of Methanol from СО2 on Cu–Zn/xAl2O3–(1 – x)SiO2 Catalysts. Effect of Support Composition

Improved Syngas Production from Glycerol Dry Reforming: Effect of Support Composition

Glycerol to syngas conversion has been investigated under different reaction conditions like reaction temperature, feed ratio, and gas hourly space velocity (GHSV) over various binary oxides, i.e., MgO.Al 2 O 3 , CaO.Al 2 O 3 , and Al 2 O 3 prepared via a combination of simple sol-gel and wet impregnation techniques. The physicochemical characteristics of the materials were evaluated by BET, XRD, TPR, TPO, CO 2 -TPD, SEM, and TEM analysis analyses. The effects of catalyst support composition as well as metal oxides ratio in support formulation on the textural properties and catalytic performance were investigated in details. Among the examined catalysts, the Ni/CaO.Al 2 O 3 sample with 55% conversion of glycerol had a better catalytic performance in terms of activity, stability, and resistance to coke formation during reaction under the harsh reaction conditions (GHSV = 72000 ml/ (h g cat ) -1 ). The experimental results demonstrated that the Ni catalyst with an equal Ca/ AL molar ratio of support possessed the highest catalytic activity. Reaction conditions’ investigation proved that temperature and GHSV were mainly effective parameters but feed stream concentration of carbon dioxide did not directly contribute to the production of reaction products.

Nickel-Containing Ceria-Zirconia Doped with Ti and Nb. Effect of Support Composition and Preparation Method on Catalytic Activity in Methane Dry Reforming.

Nickel-containing mixed ceria-zirconia oxides also doped by Nb and Ti have been prepared by a citrate route and by original solvothermal continuous flow synthesis in supercritical alcohols. Nickel was subsequently deposited by conventional insipient wetness impregnation. The oxides are comprised of ceria-zirconia solid solution with cubic fluorite phase. Negligible amounts of impurities of zirconia are observed for samples prepared by citrate route and doped by Ti. Supports prepared by supercritical synthesis are single-phased. XRD data, Raman, and UV-Vis DR (diffuse reflectance) spectroscopy suggest increasing lattice parameter and amount of oxygen vacancies in fluorite structure after Nb and Ti incorporation despite of the preparation method. These structural changes correlate with the catalytic activity in a methane dry reforming reaction. Catalysts synthesized under supercritical conditions are more active than the catalysts of the same composition prepared by the citrate route. The catalytic activity of samples doped with Ti and Nb is two times higher in terms of TOF (turnover frequency) and increased stability of these catalysts is attributed with the highest oxygen mobility being crucial for gasification of coke precursors.

Mesoporous copper-ceria-titania ternary oxides as catalysts for environmental protection: Impact of Ce/Ti ratio and preparation procedure

Hydrothermally obtained mesoporous ceria-titania mixed oxides with different composition are modified with copper using incipient wetness impregnation and “chemisorption-hydrolysis” techniques. Their catalytic properties in methanol decomposition as a source of hydrogen and total oxidation of ethyl acetate as representative volatile organic pollutant are investigated. The effect of support composition and modification method on the formation of catalytic active sites is studied. The obtained results show that the catalytic behavior is determined by the activity of finely dispersed CuO crystallites and facile electron transfer in the “conjugated” TiCeCu redox centres in the interface layer. The mechanism of the formation of the interface layer and the growth of CuO crystallites during different modification procedures are discussed in details. The mesoporous CuCeTi oxides demonstrate excellent catalytic activity in total oxidation of ethyl acetate. Their catalytic behavior in methanol decomposition is strongly influenced by the reductive transformations, which are provoked by the reaction medium.

Effect of LDH composition on the catalytic activity of Ru/LDH for the hydrolytic dehydrogenation of ammonia borane

The hydrolytic dehydrogenation of ammonia borane (NH3-BH3, AB for short) in the presence of catalysts has been identified to be a safe and efficient way for hydrogen release. Understanding the dehydrogenation mechanism of AB is helpful and important to design efficient catalysts. So far, although the effects of various factors on dehydrogenation of AB have been studied, such as the noble metal particle size effect, crystal-phase effect and the support crystal plane effect, the effect of support composition on dehydrogenation of AB has rarely been reported yet. In this study, we choose composition-adjustable layered double hydroxide (MgAl-LDHs) as support for Ru nanoparticles, and use the as-prepared catalysts for comparing their catalytic activity towards the dehydrogenation of AB. The catalytic results demonstrate the catalytic activity of Ru/MgAl-LDHs is related to MgAl-LDHs composition, exhibiting a support-composition effect in the hydrolytic dehydrogenation of AB. Combining various characterizations, the different composition of MgAl-LDHs has an effect on the interaction between Ru nanoparticles and MgAl-LDHs, which directly affects the catalytic activity for the hydrolysis of AB. This study provides new important fundamental knowledge on the mechanism of AB hydrolysis over practical supported metal catalysts which can be used for a better catalyst design.

Effect of support composition on the structural and catalytic properties of Ru/AlOOH–SiO2catalysts for benzene selective hydrogenation

A volcano-type correlation between the acid amount and cyclohexene selectivity over the Ru/AlOOH–SiO2catalysts was elucidated in benzene selective hydrogenation.

Effect of support composition on the origin and reactivity of carbon formed during dry reforming of methane over 5 wt% Ni/Ce1−xMxO2−δ (M = Zr4+, Pr3+) catalysts

Carbon dioxide reforming of methane to synthesis gas in the 550–750°C range over 5wt% Ni/Ce1−xMxO2−δ (M=Zr4+, Pr3+) solids has been investigated with respect to the effects of support chemical composition and reaction temperature on the amount, reactivity (towards H2 and O2) and relative contribution of CH4 and CO2 activation routes towards “carbon” formation. For these “carbon” characterisation studies, various transient isothermal and temperature-programmed oxidation (TPO) and hydrogenation (TPH) experiments coupled with the use of 13CO and 13CO2 isotope gases were conducted. TPO following dry reforming (5%13CO2/5%12CH4/45%Ar/45%He) demonstrated that the relative amount of the various kinds of “carbon” formed via the CH4 and CO2 activation routes was strongly dependent on reaction temperature and support chemical composition. At 550°C, the ratio of 12CO2 to 13CO2 of the 12C-containing and 13C-containing inactive “carbon” formed was 0.4, 0.27 and 0.19, whereas at 750°C was 1.07, 1.06 and 0.29, respectively, for the 5wt% Ni supported on Ce0.8Zr0.2O2, Ce0.8Pr0.2O2 and Ce0.5Zr0.5O2 carriers. The origin of “carbon” formation via the CO2 activation route was illustrated to be the Boudouard reaction (2CO-s→CO2(g)+C-s+s) through a transient isotopic experiment with a feed gas containing 13CO and 12CH4. It was also found that CO-s derived from the direct dissociation of CO2 and the CH4 activation route can lead to a number of different kinds of “carbon” which depends on support chemical composition. The present 5wt% Ni/Ce0.8Pr0.2O2 catalytic system exhibited CO2 conversion of 84%, H2-yield of 48%, and H2/CO ratio of 1.04 after 50h of dry reforming of methane at 750°C (20% CH4, 20% CO2, He; GHSV=30,000h−1) with a relatively low amount (17.5mgC/gcat or 1.75wt%) of accumulated inactive “carbon”. The support chemical composition was found to influence the nickel particle size, which in turn influenced the origin, kinetics and the reactivity of “carbon” deposition under dry reforming reaction conditions.

Hydrogen production by autothermal reforming of methane over NiPd catalysts: Effect of support composition and preparation mode

NiPd/Ce0.5Zr0.5O2/Al2O3 and NiPd/La2O3/Ce0.5Zr0.5O2/Al2O3 catalysts were prepared by incipient wetness co-impregnation method or sequential impregnation method for autothermal reforming of methane (ATR of CH4). The influence of the preparation mode, Ce0.5Zr0.5O2 and La2O3 additives on the physicochemical properties of NiPd supported catalysts and the effect on their activity to produce hydrogen by ATR of CH4 were investigated. Characterization of fresh and spent Ni-based catalysts by X-ray fluorescence spectroscopy, N2 adsorption, X-ray diffraction, H2 temperature-programmed reduction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were performed. It was demonstrated that support composition determines NiO dispersion as well as reducibility of Ni species through different strength of Ni-support interaction. The preparation method modifies the phase composition and catalyst ability for reduction. The catalyst evolution under reaction conditions was studied. The NiO (∼15 nm) and NiPd alloy (∼18 nm) phases were observed in the spent catalysts. It was found that the Nio/NiO ratio can be regulated by support composition and preparation mode of catalysts. It is demonstrated that studied catalysts provide high methane conversion of 90–100%, CO yield of 55–85% and H2 yield of 55–75% in ATR of CH4 at 750–950 °C. The optimal composition and preparation method of catalyst were selected. The best ATR of CH4 performance is provided by 10 Ni0.5Pd/10Ce0.5Zr0.5O2/Al2O3 catalyst prepared by Pd/Ni sequential impregnation method that can be associated with peculiarity of NiPd particles structure and the optimal ratio between NiO species with different ability for reduction.

Dehydration of glycerin to acrolein over H3PW12O40 heteropolyacid catalyst supported on silica-alumina

A series of tungstophosphoricacid (H3PW12O40) catalysts supported on silica-alumina (SA-X (X=0, 15, 30, 50, 70, 85, and 100)) with different SiO2 content (X, mol%) were prepared, and they (H3PW12O40/SA-X) were applied to the gas-phase dehydration of glycerin to acrolein. The effect of support composition on the physicochemical properties and catalytic activities of H3PW12O40/SA-X catalysts was investigated. Total acidity and Brønsted acidity of H3PW12O40/SA-X catalysts determined from pyridine-adsorbed in situ FT-IR spectroscopy measurements showed volcano-shaped trends with respect to SiO2 content. Among the catalysts, H3PW12O40/SA-50 exhibited the largest total acidity while H3PW12O40/SA-85 showed the largest Brønsted acidity. The results of 27Al NMR spectroscopy analyses of H3PW12O40/SA-X (X=15, 30, 50, 70, and 85) catalysts clearly demonstrated that Brønsted acidity of the catalysts was proportional to the amount of AlIV species. It was revealed that yield for acrolein increased with increasing Brønsted acidity rather than total acidity of H3PW12O40/SA-X catalysts. Among the catalysts tested, H3PW12O40/SA-85 with the largest Brønsted acidity showed the highest yield for acrolein. A synergistic effect between H3PW12O40 and SA-85 for H3PW12O40/SA-85 catalyst was also observed in the dehydration of glycerin to acrolein. Moreover, the catalytic performance of regenerated H3PW12O40/SA-85 catalyst was almost recovered compared to that of fresh H3PW12O40/SA-85 catalyst.

Effect of support composition and metal loading on Au/Ce1−xZrxO2 catalysts for the oxidative steam reforming of methanol

Gold (Au) deposited on CeO2–ZrO2 mixed oxides, prepared by the co-precipitation (CP) technique, was tested for oxidative steam reforming of methanol (OSRM) in the temperature range of 200–400°C. An active uniform Ce1−xZrxO2 solid solution was found to be dependent on the Zr/(Ce+Zr) ratio and the calcination temperature of the support, where a ratio of 0.25 calcined at 400°C efficiently performed Zr4+ incorporation inside the Ce4+ lattice to produce smaller ceria crystallites and higher surface area. The highest methanol conversion obtained was 92% at 400°C, while H2 and CO concentrations were observed at 16% and 0.25%, respectively. The variation in Au content significantly affected the Au particle size, where Au agglomeration appeared at the highest loading of 5wt%, while the 3wt% Au had optimum particle size at 21nm, which was suitable for OSRM. When comparing the stability behaviors of the Au/CeO2 and Au/Ce0.75Zr0.25O2 catalysts at 350°C, the solid solution supports had higher catalytic activity with a longer life-time and less coke formation via coke gasification, as the main factor of catalyst deactivation, than those of the Au/CeO2 catalyst.

Effect of support composition on the activity of Pt and PtMo catalysts in the conversion of n-hexadecane

The SiO2Al2O3 material and mesoporous molecular sieves of AlSBA-15 type described in this work were applied as the supports for the Pt and PtMo catalysts. Catalysts were synthesized by one step impregnation, i.e. Pt catalysts with 1wt.% of Pt as well as by two step impregnation, i.e. PtMo catalysts with 4–8wt.% of Mo followed by 1wt.% of Pt. The activity of the catalysts was investigated in n-C16 conversion (5MPa; 320–370°C; WSHV, 3.5h−1; H2:CH, 350:1Nm3/m3) and in n-C7 conversion (0.1MPa; 350–370°C; WHSV, 1h−1; H2:CH, 10:1mol/mol). The results have shown that at comparable reaction temperatures, i.e. 340–360°C the catalysts containing AlSBA-15 are more active than the catalysts supported on SiO2Al2O3. Among the PtMo/AlSBA-15 catalysts, the catalyst containing 8wt.% of Mo provides the highest selectivity towards i-C16 and the highest iso/n proportion within C10–C15 fraction together with the maintenance of a high conversion. SEM examinations of PtMo catalysts have shown that type of support influences Mo distribution; agglomerates of Mo phases are observed on the AlSBA-15 containing catalysts. It was postulated that the weaker Mo–support interactions and higher acidity in AlSBA-15 supported catalysts resulted in a more active and selective catalyst for hydroconversion of n-hexadecane.

Effect of support composition and metal loading on Au catalyst activity in steam reforming of methanol

Gold (Au) supported on CeO2–Fe2O3 catalysts prepared by the deposition-coprecipitation technique were investigated for steam reforming of methanol (SRM). The 3 wt% Au/CeO2–Fe2O3 sample calcined at 400 °C achieved 100% methanol conversion and 74% hydrogen yield due to a strong Ce–Fe interaction in the active solid solution phase, CexFe1−xO2. The sintering of Au particles was observed when the highest metal content of 5 wt% was registered, which worsened the SRM activity. According to the TPR and TPO analysis, it was found that the transformation of the α-Fe2O3 structure in the mixed oxides and the coke deposition were the main factors for the rapid deactivation of the catalyst.

Methane dry reforming on Ni/Ce0.75Zr0.25O2–MgAl2O4 and Ni/Ce0.75Zr0.25O2–γ-alumina: Effects of support composition and water addition

Nickel catalysts (10wt.%) supported on MgAl2O4 and γ-Al2O3 were prepared by the wet impregnation method and promoted with various contents of Ce0.75Zr0.25O2. X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), H2-temperature programmed reduction (TPR) and CO2-temperature programmed desorption (TPD) were employed to observe the characteristics of the prepared catalysts. Ni/γ-Al2O3 and Ni/Ce0.75Zr0.25O2 (5wt.%)–MgAl2O4 showed better activity in CO2 methane reforming with 75.7(0.93) and 75.4(0.82) CH4 conversions (and H2/CO ratio). H2O was added to feed in the range of H2O/(CH4+CO2): 0.1–0.5 to suppress reverse water gas shift (RWGS) effect and adjusting H2/CO ratio. The CH4 conversions (and H2/CO) increased to 81(1.1) with 0.5 water/carbon mole ratio in Ni/γ-Al2O3 and 85(1.2) with 0.2 water/carbon mole ratio in Ni/Ce0.75Zr0.25O2 (5wt.%)–MgAl2O4. The stability of Ni/Ce0.75Zr0.25O2 (5wt.%)–MgAl2O4 in the presence and absence of water was investigated. Coke formation and amount in used catalysts were examined by SEM and TGA, respectively. The results showed that the amount of carbon was suppressed and negligible coke formation (less than 3%) was observed in the presence of 0.2 water/carbon mole ratio over Ni/Ce0.75Zr0.25O2 (5wt.%)–MgAl2O4 catalyst.

Preparation and Ultra-Deep Hydrorefining Performance of Ni-P/Al<sub>2</sub>O<sub>3</sub>-ZrO<sub>2</sub> Catalysts

A series of Al2O3-ZrO2 (AZ-X) composite oxides with different ZrO2 contents were prepared by a chemical precipitation method. Ni-P/AZ-X catalysts were prepared by temperature-programmed reduction. The supports and catalysts were extensively characterized by X-ray diffraction (XRD) and BET. The effects of support composition and P/Ni molar ratios on the catalytic performance of the catalysts were investigated by thiophene hydrodesulfurization (HDS) and pyridine hydrodenitrogenation (HDN). In comparison with Al2O3, Al2O3-ZrO2 (20 wt% ZrO2) composite oxide supported Ni-P catalyst exhibited higher activity and the activities of HDS and HDN increased by 7.5 % and 11.1 %, respectively. Studies of Ni-P/AZ-X catalysts with varying initial P/Ni molar ratios indicated that oxidic precursors with molar ratios of P/Ni = 2/1 yielded catalyst containing phase-pure Ni2P which exhibited optimal activity.

Oxidative steam reforming of ethanol over Rh based catalysts in a micro-channel reactor

Oxidative steam reforming of ethanol (OSRE) was studied over Rh/CeO 2/Al 2O 3 catalysts in a micro-channel reactor. First, the catalyst support, Al 2O 3, was deposited on to the metallic substrate by washcoating and then the CeO 2 and active metal were sequentially impregnated. The effect of support composition as well as active metal composition on oxidative steam reforming of ethanol in a micro-channel reactor was studied at atmospheric pressure, with water to ethanol molar ratio of 6 and oxygen to ethanol molar ratio ranging from 0.5 to 1.5, over a temperature range of 350–550 °C. Ceria added to 1%Rh/Al 2O 3 showed higher activity and selectivity than 1%Rh/Al 2O 3 alone. Out of the various catalysts tested, 2%Rh/20%CeO 2/Al 2O 3 performed well in terms of activity, selectivity and stability. The OSRE performance was compared with that of SRE over 2%Rh/20%CeO 2/Al 2O 3 catalyst at identical operating conditions. Compared to SRE, the activity in OSRE was higher; however the selectivity to desired products was slightly lower. The H 2 yield obtained in OSRE was ∼112 m 3 kg −1 h −1, as compared to ∼128 m 3 kg −1 h −1 in SRE. The stability test performed on 2%Rh/20%CeO 2/Al 2O 3 at 500 °C for OSRE showed that the catalyst was stable for ∼40 h and then started to deactivate slowly. The comparison between packed bed reactor and micro-channel reactor showed that the micro-channel reactor can be used for OSRE to produce hydrogen without any diffusional effects in the catalyst layer.

Effects of support composition and pretreatment on the activity and selectivity of carbon-supported PdCu nCl x catalysts for the synthesis of diethyl carbonate

The oxidative carbonylation of ethanol to diethyl carbonate (DEC) has been investigated on catalysts prepared by dispersing CuCl 2 and PdCl 2 on activated carbon and carbon nanofibers. The objectives of this work were to establish the effects of support structure and pretreatment on the dispersion of the catalytically active components and, in turn, on the activity and selectivity of the catalyst for DEC synthesis. At the same surface loading of CuCl 2 and PdCl 2, partially oxidized carbon nanofibers resulted in a higher dispersion of the active components and a higher DEC activity than could be achieved on activated carbon. Catalyst characterization revealed that nearly atomic dispersion of CuCl 2 and PdCl 2 could be achieved on the edges of the graphene sheets comprising the carbon nanofibers. Over oxidation of the edges or their removal by heat treatment of the nanofibers resulted in a loss of catalyst activity. The loss of catalyst activity with time on stream could be overcome by the addition of ppm levels of CCl 4 to the feed. While catalysts prepared with CuCl 2 alone were active, a fivefold increase in activity was realized by using a PdCl 2/CuCl 2 ratio of 1/20. It is proposed that the Pd 2+ cations interact with [CuCl 2] − anions to form Pd[CuCl 2] 2 complexes that are stabilized through dative bonds formed with oxygen groups present at the edges of the graphene sheets of the support. A mechanism for DEC synthesis is discussed, and a role for the Pd 2+ cations as part of this mechanism is proposed.

Steam reforming of ethanol over Rh/CeO2/Al2O3 catalysts in a microchannel reactor

Steam reforming of ethanol was studied over Rh/CeO2/Al2O3 catalysts in a micro-channel reactor. First, the catalyst support was deposited on to the metallic substrate by washcoating and then the CeO2 and active metal were sequentially impregnated. The catalysts were characterized by means of BET surface area, temperature programmed reduction, H2 chemisorption and atomic absorption spectroscopy. The effect of support composition as well as active metal composition on steam reforming of ethanol in micro-channel reactor was studied at atmospheric pressure, with an ethanol to water molar ratio of 1:6, over a temperature range of 400–600°C. Ceria added to 2%Rh/Al2O3 showed higher activity and selectivity than 2%Rh/Al2O3 alone. With addition of Ni to 2%Rh/20%CeO2/Al2O3, the catalyst activity was significantly reduced. Out of the various catalysts tested, 2%Rh/20%CeO2/Al2O3 performed well in terms of activity, selectivity and stability. The micro-channel reactor performance was compared with that of packed bed reactor using 2%Rh/20%CeO2/Al2O3 catalyst at identical operating conditions. The activity was similar in both the reactors but the selectivity to desired products were higher in the micro-channel reactor. The H2 yield obtained in the micro-channel reactor was ∼65Lg−1h−1, as compared to 60LH2g−1h−1 in the packed bed reactor. The stability test performed on 2%Rh/20%CeO2/Al2O3 at 500°C in the micro-channel reactor showed that the catalyst was stable for ∼35h and then started to deactivate slowly.

The effect of support on redox properties and methanol-oxidation activity of vanadia catalysts

The effect of support composition on the catalytic properties of isolated mono-vanadates was studied using reaction rates for the methanol-oxidation reaction and oxygen binding from coulometric titration measurements on 2.5 wt% V 2O 5/ZrO 2, 2.5 wt% V 2O 5/TiO 2, and 5 wt% V 2O 5/Al 2O 3. Although a review of the redox properties for the bulk oxides V 2O 5, ZrV 2O 7, AlVO 4, Mg 3(VO 4) 2, and CeVO 4 showed that the environment surrounding the V cations can have a dramatic effect on the redox properties, the majority of sites on supported catalysts showed nearly identical properties, with Δ G of oxidation being −375 ± 25 kJ/mol at 748 K. The steady-state turnover frequencies for methanol oxidation were also similar (within a factor of 3) on each of the supports over the temperature range from 463 to 528 K. Finally, methanol-oxidation rates in the absence of oxygen over the oxidized vanadia/titania catalyst at 443 K demonstrated that all of the vanadia sites were active for the reaction and exhibited a similar rate to that observed in the presence of oxygen, showing that the reaction follows a Mars-van Krevelen mechanism.

Preferential oxidation of CO in H2-rich stream over CuO/Ce1−xTixO2 catalysts

CuO/Ce1−xTixO2 prepared by sol–gel impregnation was used as catalysts for the preferential oxidation (PROX) of CO in H2-rich stream. The effects of support composition, catalyst calcination temperature as well as the presence of H2O and CO2 in the reaction stream on the catalytic performance of CuO/Ce1−xTixO2 were investigated. The results indicated that the catalyst CuO/Ce0.8Ti0.2O2 exhibits the highest activity and the optimal temperature for the catalyst calcination is 500°C. The presence of H2O and CO2 in the reaction stream has a negative effect on the catalytic activity and stability of CuO/Ce0.8Ti0.2O2. The negative effect of CO2 on the catalyst stability is stronger than that of H2O, suggesting that the accumulation of carbonate species may be the main reason for catalyst deactivation. The characterization by means of XRD, HRTEM, and H2-TPR indicated that the doping of TiO2 in CeO2 enhances the surface area of the composite oxide support, decreases its particle size, and promotes the dispersion of active copper species. The strong interaction between TiO2 and CeO2 in the support as well as the interfacial interaction between CuO and the support may also contribute to the high catalytic activity of CuO/Ce0.8Ti0.2O2.