三维有序大孔钙钛矿型氧化物LaFe_(0.7)Co_(0.3)O_3的合成及甲烷化学链水蒸气重整性能

采用无皂乳液聚合法制备聚苯乙烯(PS)微球,通过自组装得到排列均匀有序的聚苯乙烯(PS)胶晶模板,然后经过浸渍和煅烧得到三维有序大孔(3DOM)钙钛矿型氧化物LaFe_(0.7)Co_(0.3)O_3。通过扫描电镜、透射电镜和X射线衍射等手段对制备的3DOM钙钛矿型氧化物LaFe_(0.7)Co_(0.3)O_3的物理化学性能进行表征。在固定床反应器上考察3DOM LaFe_(0.7)Co_(0.3)O_3的甲烷化学链水蒸气重整性能。结果表明,聚苯乙烯(PS)微球粒径受苯乙烯单体使用量的影响,随着苯乙烯单体使用量的增加聚苯乙烯(PS)微球粒径呈增大的趋势;煅烧温度对三维有序大孔结构有显著影响,浸渍后模板在500℃煅烧下即能形成三维有序大孔结构比表面积达到19.820 m2/g,随着煅烧温度的升高三维有序大孔结构遭到部分破坏,在900℃煅烧下三维有序大孔结构遭到完全破坏。在氧载体与甲烷的反应前期,气体产物中CO2含量较高,是表面吸附氧将甲烷完全氧化所致,在表面吸附氧消耗完后体相晶格氧将甲烷部分氧化生成H2与CO。在水蒸气氧化阶段,水蒸气与还原态的氧载体发生反应生成氢气,产氢率为4.0-5.0 mmol/g。同时水蒸气氧化阶段气相产物中CO和CO2含量很低,说明3DOM LaFe_(0.7)Co_(0.3)O_3具有优秀的抗积炭性能。     

THE ROLE OF LATTICE AND GASEOUS OXYGEN ON THE OXIDATIVE COUPLING OF METHANE STUDIED BY A PULSE REACTION TECHNIQUE

A comparative study of the role of lattice and gaseous oxygen in theoxidative coupling of methane over Na~ /Cao and Ca_xSr_(1-x)TiO_3 perovskiteoxide catalysts was performed by using a pulse reaction technique with CH_4,O_2 and mixtures of CH_4and O_2.It was found that there is an oxygen species onthe Surface of Cao which is active only for the total oxidation of methane at thereaction temperature.These oxygen species.once reacted with methane andconsumed,can be regenerated by the adsorption of oxygen molecules from thegas phase or by the migration of the lattice oxysen from the bulk onto thesurface.In contrast,no such oxygen species and no reaction can be detected bymethane pulsed over Ca_xSr_(1-x)TiO_3perovskite oxide catalysts.Na~ can heavilysuppress the non-selective oxygen species on the surface,and When 5mol%Na~ was incorporated onto the surface of Cao,the sample showed no reactivityto methane.When oxygen exists in the gas phase,or the pulse containsmethane and oxygen,the reaction over(Cao is mai     

Hydrogen and syngas production from two-step steam reforming of methane using CeO2 as oxygen carrier

CeO2 oxygen carrier was prepared by precipitation method and tested by two-step steam reforming of methane (SRM). Two-step SRM for hydrogen and syngas generation is investigated in a fixed-bed reactor. Methane is directly converted to syngas at a H2/CO ratio close to 2 : 1 at a high temperature (above 750 °C) by the lattice oxygen of CeO2; methane cracking is found when the reduction degree of CeO2 was above 5.0% at 850 °C in methane isothermal reaction. CeO2?δ obtained from methane isothermal reaction can split water to generate CO-free hydrogen and renew its lattice oxygen at 700 °C; simultaneously, deposited carbon is selectively oxidized to CO2 by steam following the reaction (C+2H2O→CO2+2H2). Slight deactivation in terms of amounts of desired products (syngas and hydrogen) is observed in ten repetitive two-step SRM process due to the carbon deposition on CeO2 surface as well as sintering of CeO2.     

A modified combustion method for the determination of the surface and bulk carbon contents of high-purity metals

A newly developed apparatus for the determination of carbon in high-purity metals is described. By controlled heating of samples in an oxygen or oxygen/helium flow, it is possible to distinguish between the carbon contents of a thin surface layer and of the bulk metal. The oxidation is done within a device of fused silica by means of micropyrometer-controlled h.f. induction heating. The carbon dioxide formed is quantified after absorption in 10^-2 M sodium hydroxide by measurement of electrolytic conductivity. Calibration is done by injection of various volumes of a certified calibration gas from a gas syringe. Investigations on Si, Fe, Ni, Cu, Zr, Nb, Mo and W samples of high purity as well as of technical grade showed that the surface carbon can be determined by oxidation at 630–650°C. Its quantity depends on the kind of sample preparation chosen. Increasing the temperature to a maximum of 1500°C yields the carbon concentration of the bulk by complete combustion of the sample. Combustion additives are useful for a variety of matrices. At sample weights of ? 0.5 g, bulk carbon concentrations of ? 0.1 μg g^-1 can be determined.     

Study of the interactions between carbon monoxide and high specific surface area tin dioxideThermogravimetric analysis and FTIR spectroscopy

The interactions of CO with a high specific surface area tin dioxide was investigated by FTIR spectroscopy and thermogravimetric analysis. FTIR study of CO interactions have shown that CO can adsorb on cus (coordinatively unsaturated sites) Sn⁴⁺ cation sites (band at 2201 cm^-1). In addition, CO reacts with surface oxygen atoms. This leads to the partial reduction of SnO₂ surface and to the formation of ionised oxygen vacancies together with the release of free electrons, which are responsible for the loss of transmission. Formed CO₂ can chemisorb on specific surface sites: on basic sites to form carbonates species and on acidic sites (Sn⁴⁺-CO₂ species) which is in competition with the formation of Sn⁴⁺-CO species. TG experiment have shown that the reduction of SnO₂ by CO at 400°C occurs in two steps. First, the reduction of SnO₂ surface, which is a quick phenomenon. This has allowed to evaluate that more than 12% of reducible surface oxygens can react with CO, essentially because of the presence of a large amount of surface hydroxyl groups. The second step of the reduction of SnO₂ would be the progressive reduction of SnO₂ bulk by the slow diffusion of oxygen atoms from the bulk to the surface. This revised version was published online in July 2006 with corrections to the Cover Date.     

Al (110) surface oxide thermal stability in ultrahigh vacuum

This research characterizes the stability of the Al₂O₃ surface oxide on Al (110) as a function of temperature and within an ultrahigh vacuum environment (p < 5 × 10^?12 Torr). Auger electron spectroscopy and temperature desorption spectroscopy were used to correlate the change in oxygen and carbon surface concentration. The surface oxide was observed to remain stable up to 350–400 °C. Above this temperature, the oxide began to dissociate resulting in a CO desorption peak at 425 °C followed by extensive dissolution of the C and O into the Al bulk. A second and much smaller CO desorption peak was observed at 590 °C in concert with complete oxide breakdown and the virtual disappearance of surface carbon and oxygen. Extrapolation of the Auger electron spectral ratios of C_KLL and O_KLL peaks to the sum of the Al⁰_LVV and Al³⁺_LVV peak suggests that the surface concentration of each approaches zero at ~640 °C. The predominant mechanism for reduction of the surface oxide occurs by dissolution into the bulk instead of desorption. Copyright © 2013 John Wiley & Sons, Ltd.     

Forms of oxygen in La1 − x Ca x MnO3 + δ (x = 0–1) perovskites and their reactivities in oxidation reactions

The effects of substitution in the cationic sublattice and of the synthesis procedure on the reactivity of different forms of oxygen in La_{1 ? x} Ca _x MnO_{3 + δ} perovskites synthesized by mechanochemical and ceramic processing was studied by temperature-programmed reduction (TPR) with hydrogen. As the calcium content of the perovskite is raised, the maxima of the TPR peaks shift to lower temperatures and the extent of reduction of the perovskite increase, implying an increase in the reactivity of the system. Conversely, raising the calcination temperature or extending the calcination time shifts the maxima of the peaks to higher temperatures and diminishes the extent of reduction of the sample. TPR data for the intermediate-composition samples can be explained in terms of the dependence of microstructure on the synthesis procedure (near-surface calcium segregation in the mechanochemically synthesized samples and the microheterogeneous structure of the ceramic samples). The reduction process Mn⁴⁺ → Mn²⁺ takes place in the low- and medium-temperature regions. According to the literature, the bulk reduction process Mn³⁺ → Mn²⁺ occurs at high temperatures. The activity of the system in CO oxidation is correlated with the amount of the most reactive surface oxygen, which is eliminated in hydrogen TPR runs below 250–300°C.     

稀土Pr_6O_(11)表面上低碳烃氧化反应的原位FT-IR研究

前文报道了CO与Pr_6O_(11)表面反应的结果.已发表的关于烃类与氧化物表面反应的研究,旨在了解烃类的活化和表面氧化机理,而且大部分工作都是在过渡金属氧化物上进行的.近年来的研究表明,稀土氧化物将是有潜力的甲烷氧化偶联制乙烯的催化剂,在消除环境污染的烃类完全氧化催化剂中,稀土氧化物也常被用作助剂或活性组分,但对于稀土氧化物本身的催化表面研究尚不多见.作者曾较系统地研究了CeO_2的表面催化性质,发现表面上存在多种氧物种,这些氧物种与烃类的反应活性差异很     

The Heterogeneous Reaction of Ozone on Carbonaceous Surfaces

Ozone, O₃, reacts with a carbon sample at room temperature. Clean carbon samples show a half to one and a half order of magnitude increased initial rate constant (k₀) for O₃ loss relative to repetitively exposed carbon samples. The ozone loss rate and therefore the rate constant reaches steady state (k_ss) on the time scale of tens of minutes, upon exposure to a characteristic dose of 8 × 10¹⁷ molecules for a 30-mg carbon sample independent of the flow rate. This characteristic dose closely corresponds to a monolayer of adsorbed ozone molecules on the carbon sample. Both k₀ and k_ss decrease with increasing flow rate of O₃ into the reactor, and the loss rate is found to depend on [O₃]. When the loss rate is plotted against the steady state concentration of O₃, a saturation plot results which is proportional to the surface coverage, θ, at a given [O₃].This interpretation rests upon a Langmuir type kinetics model with an assumed first-order dependence of the loss rate constant. The “sticking coefficients” track the rate constants and are on the order of 10^?3 to 10^?5 depending on the carbon sample, dose, and flow rate. Furthermore, k_o depends on the length of the dark period (absence of O₃ exposure) and is larger the longer time the sample has had to recuperate from previous O₃ exposures up to a period of 150 s. This surface relaxation is thought of as a time-dependent change in surface coverage taking place in the dark period and is therefore an indication of a slow surface diffusion/reaction that can be separated from the adsorption-desorption kinetics. The mass balance shows that for every ozone molecule that is lost on the surface, an oxygen molecule is found. This adsorbed odd oxygen is then responsible for product formation, which comprises the volatile components CO and CO₂ to an extent of 20 to 40% of the odd oxygen deposited on the surface. The difference is thought to be in a preoxidized state on the carbon sample, which evolves CO and CO₂ upon heat treatment.     

Properties of cerium-zirconium mixed oxides partially substituted by neodymium: Comparison with Zr-Ce-Pr-O ternary oxides

CeO₂ doped with praseodymium, neodymium and/or zirconium atoms were prepared by coprecipitation and by the sol-gel method. Structural properties were investigated by in situ XRD and Raman spectroscopy while oxygen storage capacity (OSC) was measured by transient CO oxidation. All the compounds, except pure Nd₂O₃, have a fluorite-type structure as well as a Raman band at 560 cm⁻¹ characteristic of the oxygen vacancies involving non-stoichiometric oxides. The lattice parameter under hydrogen, being dependent on the temperature, revealed two reduction mechanisms: one at a low temperature at the surface and another at a high temperature in the bulk. Ce-Nd binary oxides show a strong tendency towards crystallite aggregation, which reduces accessibility to gases and OSC properties. Zirconium improves the thermal resistance to sintering of both Ce-Nd and Ce-Pr oxides. The Zr-Ce-Pr-O followed by Zr-Ce-Nd-O compounds displaying high oxygen mobility at a low temperature, appear to be very promising for practical applications such as OSC materials.     

Studies on the Surface Oxygen Species and the Catalytic Activity for CO Oxidation of La1-xSrxCo1-xMnxO3, a Perovskite-Type Oxides Catalyst

The surface oxygen distribution the active oxygen species for CO on the perovskite-type catalyst La_1-xSr_xCo_1-xMn_xO₃ and its catalytic oxidation activity with CO as probe were investigated by means of XRD, TPD and XPS in a continuous flow microreactor. Results showed that different adsorbed oxygen species and lattice oxygen were distributed on the catalyst surface. Meanwhile, the surface lattice oxygen of the oxides was reacting in the course of CO oxidation. This leads to the conclusion that, when x=0.6, the catalyst shows the best oxidative activity and lower starting temperature.     

Oxygen species and their reactivity in the mechanochemically prepared substituted perovskites La1 ? xSrxCoO3 ? y (x = 0–1)

The oxygen species and their reactivity in the mechanochemically prepared substituted perovskites La_{1 − x} Sr _x CoO_{3 − y} were studied using temperature-programmed reduction (TPR) of the samples with hydrogen. The experimental data were compared with data on the catalytic activity of the series of La_{1 − x} Sr _x CoO_{3 − y} catalysts in the oxidation of CO, as well as with the real structures and surface compositions of the samples, which were studied in detail previously. As the strontium content was increased, the degree of reduction of the samples increased in the course of TPR and the TPR peaks shifted to the region of lower temperatures, except for the last sample containing no lanthanum (x = 1). An increase in the calcination temperature and time resulted in a decrease in TPR peak intensities and in a shift of the peaks to the region of higher temperatures. A reaction scheme was proposed for the reduction. In accordance with this reaction scheme, Co⁴⁺ in substituted cobaltites was reduced to Co⁰ at temperatures lower than 400°C. In the temperature region of 400–500°C, the Co³⁺ → Co²⁺ bulk reduction, as well as the deep reduction processes Co³⁺ → Co⁰ and Co⁴⁺ → Co⁰, occurred; substitution facilitated the above processes. At temperatures higher than 500°C, Co²⁺ → Co⁰ bulk reduction occurred. The observed reduction of the mechanochemically prepared samples depended on their microstructure, which was described previously. It was found that the activity of the samples in the oxidation of CO depends on the amount of the most weakly bound reactive surface oxygen species, which were removed in TPR with hydrogen to 150°C. No correlation between the amount of strongly bound (lattice) oxygen removed upon TPR and the activity of La_{1 − x} Sr _x CoO_{3 − y} samples in the oxidation of CO was found. Original Russian Text ? I.S. Yakovleva, L.A. Isupova, V.A. Rogov, 2009, published in Kinetika i Kataliz, 2009, Vol. 50, No. 2, pp. 290–299.     

Surface and structural properties of pt/ceo2catalyst under preferential co oxidation in hydrogen (PROX)

Summary Preferential oxidation of CO in the presence of excess hydrogen was studied on Pt/CeO₂with 5% metal loading. Catalytic data were similar to those observed on 1% Pt/CeO₂earlier [16]. The optimum temperature region is T￡373 K; conversion and selectivity of CO oxidation strongly decreased at higher temperatures. High-pressure XPS indicated CO adsorbed on platinum particles and significant amount of water on the ceria surface. The top-most ceria surface re-oxidized as small amount of oxygen (3%) was introduced into the H₂/CO feed. Despite this surface re-oxidation, high-resolution TEM after reaction indicated oxygen deficient ceria bulk structure, in which the defects formed a super-cell, with CeO_1.695structure. The defective ceria is suggested to play an important role stabilizing the hydrogen bonded surface water, which (i) suppresses further hydrogen oxidation and (ii) reacts at the metal/support interface with linearly adsorbed CO in a low temperature water-gas-shift type reaction to produce CO₂.</o:p>     

Measuring oxygen yields of a thermal conversion/elemental analyzer‐isotope ratio mass spectrometer for organic and inorganic materials through injection of CO

The thermal conversion/elemental analyzer‐isotope ratio mass spectrometer (TC/EA‐IRMS) is widely used to measure the δ¹⁸O value of various substances. A premise for accurate δ¹⁸O measurement is that the oxygen in the sample can be converted into carbon monoxide (CO) quantitatively or at least proportionally. Therefore, a precise method to determine the oxygen yield of TC/EA‐IRMS measurements is needed. Most studies have used the CO peak area obtained from a known amount of a solid reference material (for example, benzoic acid) to calibrate the oxygen yield of the sample. Although it was assumed that the oxygen yield of the solid reference material is 100%, no direct evidence has been provided. As CO is the analyte gas for δ¹⁸O measurement by IRMS, in this study, we use a six‐port valve to inject CO gas into the TC/EA. The CO is carried to the IRMS by the He carrier gas and the CO peak area is measured by the IRMS. The CO peak area thus obtained from a known amount of the injected CO is used to calibrate the oxygen yield of the sample. The oxygen yields of commonly used organic and inorganic reference materials such as benzoic acid (C₆H₅COOH), silver phosphate (Ag₃PO₄), calcium carbonate (CaCO₃) and silicon dioxide (SiO₂) are investigated at different reactor temperatures and sample sizes. We obtained excellent linear correlation between the peak area for the injected CO and its oxygen atom amount. C₆H₅COOH has the highest oxygen yield, followed by Ag₃PO₄, CaCO₃ and SiO₂. The oxygen yields of TC/EA‐IRMS are less than 100% for both organic and inorganic substances, but the yields are relatively stable at the specified reactor temperature and for a given quantity of sample. Copyright © 2014 John Wiley & Sons, Ltd.     

Cleaning of Porous Aluminium Titanate by Oxygen Plasma

The removal of organic contaminants from porous Al₂TiO₅ during treatment in oxygen plasma was studied by optical emission spectroscopy (OES). The samples of Al₂TiO₅ were immersed into water emulsion of mineral oil for 3 h to get soaked. Then, they were thoroughly cleaned in ultrasound to remove oil from the surface. Samples were later exposed to RF oxygen plasma at the pressure of 75 Pa. The plasma density was about 2 × 10¹⁶ m⁻³, the electron temperature was about 6 eV and the density of neutral oxygen atoms was about 2 × 10²¹ m⁻³. Optical emission spectra between 200 and 1,000 nm were measured continuously during plasma treatment. The CO peak resulting from oil oxidation reached a well-pronounced maximum between 100 and 150 s of plasma treatment. The maximum in CO corresponded well with a minimum in O peaks. Concentration of oil in the samples was estimated by energy dispersion X-ray analysis. Initially the samples showed high concentration of carbon (about 38 at.%), while after plasma treatment the carbon concentration decreased below the detection limit. The cleaning efficiency was explained by diffusion of oil towards the surface where it was removed by oxidation with oxygen radicals.     

CO oxidation by oxygen of the catalyst and by gas-phase oxygen over (0.5–15)%CoO/ZrO<Subscript>2</Subscript>

CO adsorption on (0.5–15)%CoO/ZrО₂ catalysts has been investigated by temperature-programmed desorption and IR spectroscopy. At 20°С, carbon monoxide forms carbonyl and monodentate carbonate complexes on Co _m ²⁺ O _n ^2- clusters located on the surface of crystallites of tetragonal ZrO₂. With an increasing CoO content of the clusters, the amount of these complexes increases and the temperature of carbonate decomposition, accompanied by CO₂ desorption, decreases from 400 to 304°С. On the 5%CoO/ZrО₂ sample, the carbonyls formed on the Со²⁺ and Со⁺ cations and Со⁰ atoms decompose at 20, 90, and 200–220°С, respectively, releasing CO. At 20°С, they are oxidized by oxygen to monodentate carbonates, which decompose at 180°С. Adsorbed oxygen decreases the temperature of their decomposition on oxidation sites by ~40°C, and the sample remains in an oxidized state ensuring the possibility of subsequent CO adsorption and oxidation. The rate of the oxidation of 5%CoO/ZrО₂ containing adsorbed CO by oxygen is higher than the rate of the oxidation of the same sample reduced by carbon monoxide, because the latter reaction is an activated one. In view of the properties of the complexes, it can be concluded that the carbonates decomposing at 180°С are involved in CO oxidation by oxygen from the gas phase in the presence of hydrogen, a process occurring at 50–200°С. The rate-limiting step of this process the decomposition of the carbonates, which is characterized by an activation energy of 77–94 kJ/mol.     

DFT investigation of molybdenum (oxo)carbide formation from MoO3

The present paper summarizes theoretical investigations of geometry and electronic structure of molybdenum (oxo)carbide, whose formation is modeled by systematic replacement of lattice oxygen atoms in MoO₃ by carbon atoms or by CH₂ groups. Both, in bulk and in the small surface cluster, the formation of molybdenum (oxo)carbide is accompanied by by-products observed in experiment, namely C₂ species and CO. The present theoretical studies reveal that these are formed without reaction barrier, even though in bulk the atom mobility is limited. The thermodynamic considerations based on the obtained DFT results indicate that the process of MoO₃ reduction to yield (oxo)carbides is endoenergetic and there is no synergy between the amount of carbon already introduced to the system and the energetic cost of replacing oxygen atoms by CH₂.     

Hydrogen production from a combination of the water-gas shift and redox cycle process of methane partial oxidation via lattice oxygen over LaFeO3 perovskite catalyst

A redox cycle process, in which CH4 and air are periodically brought into contact with a solid oxide packed in a fixed-bed reactor, combined with the water-gas shift (WGS) reaction, is proposed for hydrogen production. The sole oxidant for partial oxidation of methane (POM) is found to be lattice oxygen instead of gaseous oxygen. A perovskite-type LaFeO3 oxide was prepared by a sol-gel method and employed as an oxygen storage material in this process. The results indicate that, under appropriate reaction conditions, methane can be oxidized to CO and H2 by the lattice oxygen of LaFeO3 perovskite oxide with a selectivity higher than 95% and the consumed lattice oxygen can be replenished in a reoxidation procedure by a redox operation. It is suggested that the POM to H2/CO by using the lattice oxygen of the oxygen storage materials instead of gaseous oxygen should be possibly applicable. The LaFeO3 perovskite oxide maintained relatively high catalytic activity and structural stability, while the carbonaceous deposits, which come from the dissociation of CH4 in the pulse reaction, occurred due to the low migration rate of lattice oxygen from the bulk toward the surface. A new dissociation-oxidation mechanism for this POM without gaseous oxygen is proposed based on the transient responses of the products checked at different surface states via both pulse reaction and switch reaction over the LaFeO3 catalyst. In the absence of gaseous-phase oxygen, the rate-determining step of methane conversion is the migration rate of lattice oxygen, but the process can be carried out in optimized cycles. The product distribution for POM over LaFeO3 catalyst in the absence of gaseous oxygen was determined by the concentration of surface oxygen, which is relevant with the migration rate of lattice oxygen from the bulk toward the surface. This process of hydrogen production via selective oxidation of methane by lattice oxygen is better in avoiding the deep oxidation (to CO2) and enhancing the selectivity. Therefore, this new route is superior to general POM in stability (resistance to carbonaceous deposition), safety (effectively avoiding accidental explosion), ease of operation and optimization, and low cost (making use of air not oxygen).     

Acidic and basic sites in NaX and NaY faujasites investigated by NH3, CO2 and CO molecular probes

The acid-base properties of samples of NaY and NaX faujasites have been investigated by adsorbing different probe molecules and measuring IR spectra. In the case of the NaY sample, only Na⁺ ions were found to be involved in the adsorption of CO₂ and CO, confirming the overwhelming Lewis acid character of this material. In contrast, carbonate-like species were formed by adsorbing carbon dioxide on the NaX sample, due to the reaction of basic framework oxygen atoms with CO₂ molecules polarised on neighbour Na⁺ ions. The spectroscopic analysis of NaX also showed evidence of Brønsted acid hydroxyls and OH groups bonded to extra-framework Al atoms. Ammonia adsorption revealed that the amount of Brønsted acid hydroxyls is significantly lower than the Lewis acid Na⁺ countercations. Moreover, small oxide particles, carrying carbonate-like species on their surface, are present in the zeolitic cavities. These particles could be responsible for the basic reactivity towards CO observed after outgassing the NaX sample at high temperature.     

助剂对NiMgAl催化剂的结构和甲烷二氧化碳重整反应性能的影响(英文)

向担载镍基催化剂NiMgAl中添加助剂(Co,Ir或Pt)制备了三种助剂促进型催化剂,通过氢气程序升温还原(H2-TPR),CO2/CH4程序升温表面反应(CO2/CH4-TPSR)和CO2程序升温脱附(CO2-TPD)等方法对催化剂进行表征.助剂对催化剂性能的影响通过甲烷干重整实验进行评价.添加少量的Pt或Ir助剂可以降低Ni活性组分的还原温度和提高反应性能.添加助剂的样品与原始NiMgAl催化剂相比能够降低反应的活化能,添加Co或Ir助剂的催化剂与NiMgAl催化剂相比活化能有了明显的降低.NiMgAl催化剂的活化能为51.8 kJ·mol-1,添加Pt助剂的NiPtMgAl催化剂活化能降至26.4 kJ·mol-1.NiMgAl催化剂中添加Pt助剂制备的催化剂具有较好的催化活性和较低的活化能.CH4-TPSR和CO2-TPSR结果表明添加Pt助剂可以在更低的温度下(与NiMgAl催化剂相比)提高CH4的活化能力,并在催化剂表面形成更多的碳物种.CO2-TPD结果显示,添加助剂的催化剂与NiMgAl样品相比在反应温度区间内增加了CO2的吸附/脱附量.