Hydrogenation of p-chloronitrobenzene on Ni–B Nanometal Catalysts

A series of Ni–B catalysts were prepared by mixing nickel acetate in 50% ethanol/water or methanol/water solution. The solution of sodium borohydride (1 M) in excess amount to nickel was then added dropwise into the mixture to ensure full reduction of nickel cations. The mol ratio of boron to nickel in mother solution was 3 to 1. The effects of preparation conditions such as temperature, stirring speed, and sheltering gas on the particle size, surface compositions, electronic states of surface atoms and catalytic activities of the Ni–B catalysts were studied. Ranel nickel catalyst was included for comparison. These catalysts were characterized by N₂ sorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid phase hydrogenation of p-chloronitrobenzene. All of the catalysts prepared in this study had nanosized particles. The preparation condition has significant influence on the particle size and surface compositions of the catalyst. The Ni–B catalyst was passivated by boron; therefore it was more stable than Raney nickel and did not catch fire after exposure to air. The catalysts prepared under N₂ flow could suppress the oxidation of Ni by the dissolved oxygen in water and had metallic state of nickel. The catalyst prepared with vigorous stirring at 25°C under N₂ stream yielded the smallest particles and resulted in the highest activity. It was much more active than the Raney nickel catalyst. The reaction condition also has pronounced effect on the hydrogenation activity. Using methanol as the reaction solvent increased p-chloronitrobenzene conversion to a large extent, compared to that using ethanol as the reaction medium. The selectivity of main product (p-chloroaniline) was greater than 99% on all of the Ni–B catalysts.     

Effects of Montmorillonite on the Nonisothermal Crystallization Behavior of the Poly(trimethylene terephthalate)/Polypropylene/Montmorillonite Nanocomposites

Organic montmorillonite (MMT) reinforced poly(trimethylene terephthalate) (PTT)/ polypropylene (PP) nanocomposites were prepared by melt blending. The effects of MMT on the nonisothermal crystallization of the matrix polymers were investigated using differential scanning colorimetry (DSC) and analyzed by the Avrami equation. The DSC results indicated that the effects of MMT on the crystallization processes of the two polymers exhibited great disparity. The PTT's crystallization was accelerated significantly by MMT no matter whether PTT was the continuous phase or not, but the thermal nucleation mode and three-dimensional growth mechanism remained unchanged. However, in the presence of MMT, the PP's crystallization was slightly retarded with PP as the dispersed phase, and was influenced little with PTT as the dispersed phase. When the MMT content was increased from 2_wt% to 7_wt%, the crystallization of the PTT phase was slightly accelerated, whereas the crystallization of the PP phase was severely retarded, especially at lower temperatures. Moreover, the nucleation mechanism for the PP's crystallization changed from a thermal mode to an athermal one. In the polypropylene-graft-maleic anhydride (PP-g-MAH) compatibilized PTT/PP blends, with the addition of 2_wt% MMT during melt blending, the T _c (PTT) shifted 7.8°C to lower temperature and had a broadened exotherm, whereas the T _c (PP) shifted 17.1°C to higher temperature, with a narrowed exotherm. TEM analysis confirmed that part of the PP-g-MAH was combined with MMT during blending.     

Preparation and Characterization of Silicon-containing Polyarylacetylene/montmorilloite Nanocomposites

Dimethylphenylpropargyl ammonium bromide (DMPPAB) was synthesized and used to modify pristine montmorillonite (MMT) by a cation exchange process. The organically modified montmorillonite (OMMT) was verified and used to mix with a silicon-containing polyarylacetylene (PSA) as well as MMT. The PSA/MMT and PSA/OMMT nanocomposites were prepared by solution under sonication and melting intercalation processes, respectively, and then cured by a step heating process. The thermal and flexural properties of the cured PSA and nanocomposites were studied by thermogravimetric and dynamic mechanical analysis. The results showed that the intercalation of DMPPAB into the MMT galleries made the d-spacing enlarge. During PSA curing, the cure heat of PSA caused the MMT and OMMT to delaminate and exfoliate in the PSA matrix. The glass transition temperature of the cured PSA and nanocomposites were higher than 500?°C. The inner acetylenic groups in the PSA resin could further crosslink above 300?°C. The temperature at 5% mass loss of the cured PSA decreased by 4.6% with 3% mass fraction of OMMT loading, and the char yield of the cured PSA changed only slightly. The flexural strength of the cured PSA was augmented with addition of MMT or OMMT, but the flexural modulus of the cured PSA decreased slightly. The flexural strength of the cured nanocomposite increased from 20.1?MPa to 30.1?MPa when 3% mass fraction of OMMT was added into the PSA matrix.     

Preparation and Characterization of Montmorillonite/Polypyrrole Nanocomposites by In-Situ Chemical Polymerization

After prior ultrasonic treatment of montmorillorite (MMT), montmorillonite/polypyrrole (MMT/PPy) nanocomposites containing 10–80% PPy were prepared by in-situ chemical polymerization of pyrrole at 0°C in the presence of MMT in aqueous solution with FeCl₃ as oxidant and dopant. X-ray diffraction showed an increase in the interlayer spacing from 1.26 nm for MMT to 1.55 nm for MMT/PPy-10% and 1.96 nm for MMT/PPy-80%, signifying PPy was intercalated into the MMT galleries. Infrared spectra revealed the shifts of C-N stretching vibration and in-plane deformation bands, as well as the N-H vibration peaks of PPy, suggesting the presence of interfacial interactions between MMT and PPy. Scanning electron microscopy micrographs showed a flake-like morphology for the MMT/PPy nanocomposites and the obtained PPy retained this kind of morphology after removal of MMT from the composites by Hydrofluoric acid etching, while the pristine PPy prepared under the same condition exhibited globular particles. It was found for the first time that the conductivity of MMT/PPy with more than 50% PPy was higher than that of pristine PPy, i.e. 2.72 S/cm, 3.68 S/cm, and 4.81 S/cm for MMT/PPy containing 50%, 60%, and 80% PPy, while the pristine PPy conductivity was 2.71 S/cm. Thermal gravimetric analysis suggested that the introduction of MMT clay resulted in improvement of thermal stability for the obtained nanocomposites.     

Synergistic Effect of Phosphorus-Containing Montmorillonite with Intumescent Flame Retardant in Polypropylene

Phosphorus-containing montmorillonite (P-MMT) was successfully prepared via intercalating resorcinol bis(diphenyl phosphate) (RDP) into montmorillonite (MMT) layers, and was utilized as a synergistic agent in the polypropylene/melamine pyrophosphate/pentaerythritol (PP/MPP/PER) intumescent flame retardant (IFR) system. The synergistic effect of P-MMT and IFR was investigated by dynamic mechanical analysis (DMA), thermogravimetry (TG), limiting oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), and scanning electron microscopy (SEM). It was found that P-MMT could significantly improve the thermostability and flame retardancy of the PP/IFR composite. When 2.0 wt% P-MMT replaced the same amount of IFR in the composite, both the onset decomposition temperature (T _onset) and the maximum-rate decomposition temperature (T _max) of the PP/IFR composite were increased by more than 14°C. Meanwhile, the LOI value was increased from 29.5% to 32.5%, the UL-94 rating was enhanced from V-1 to V-0, and the heat release rate (HRR), total heat release (THR), and mass lose rate (MLR) were decreased dramatically, which proved that P-MMT had a good synergistic effect with IFR in flame retardant PP.     

Ultrasound assisted co-precipitation synthesis and catalytic performance of mesoporous nanocrystalline NiO-Al2O3 powders

Mesoporous nanocrystalline NiO-Al₂O₃ powders with high surface area were synthesized via ultrasound assisted co-precipitation method and the potential of the selected samples as catalyst was investigated in dry reforming reaction for preparation of synthesis gas. The prepared samples were characterized by N₂ adsorption (BET), X-ray diffraction (XRD), Temperature programmed reduction and oxidation (TPR, TPO) and scanning electron microscopy (SEM) techniques. The effects of pH, power of ultrasound irradiation, aging time and calcination temperature on the textural properties of the catalysts were studied. The sample prepared under specified conditions (pH10, 70 W, without aging time and calcined at 600 °C) exhibited the highest surface area (249.7 m² g⁻¹). This catalyst was calcined at different temperature and employed in dry reforming of methane and the catalytic results were compared with those obtained over the catalysts prepared by impregnation and co-precipitation methods. The results showed that the catalyst prepared by ultrasound assisted co-precipitation method exhibited higher activity and stability with lower degree of carbon formation compared to catalysts prepared by co-precipitation and impregnation methods.     

碳纳米管负载Cu-Co复合氧化物的富氢气氛中CO催化消除

采用超声处理辅助浸渍法制备了多壁碳纳米管负载的Cu-Co复合氧化物催化剂. 利用XRD、TEM、H₂-TPR、XPS和Raman光谱等表征了催化剂的结构性质. 在Cu和Co氧化物以及金属氧化物与碳纳米管载体间存在强相互作用. 催化剂在富氢气氛中CO催化消除反应中,与单一Cu或Co催化剂相比,Cu-Co复合氧化物催化剂表现出独特的反应特性,特别是在较高反应温度下可同时结合CO优先氧化和CO甲烷化的反应途径来实现高效CO消除. 当Cu/Co比为1/8时活性最优,可以实现在150～250 o和高反应空速 (120 L/(h·g))富氢气氛中CO的完全消除.     

Effect of Surfactant Concentration on Thermal and Mechanical Properties of Poly(Butylene Succinate)/Organoclay Composites

Composite materials consisting of poly(butylene succinate) (PBS) and montmorillonite (MMT), modified to various extents using trihexyltetradecylphosphonium chloride (THTDP) cations, were prepared using a simple melt intercalation technique. The surfactant contents were varied, i.e. 0.4, 0.6, 0.8, 1.0, and 1.2 times the cation exchange capacity (CEC) of the MMT. The intercalation of the surfactant molecules into MMT layers, confirmed by the increase in interlayer spacing and significant changes in the morphology of the modified MMT, facilitated the dispersion of the clay in the PBS matrix. The properties of the PBS-based composites were changed with increasing surfactant content. The melting and crystallization temperatures increased and the degree of crystallinity (χ_c) decreased. The storage modulus was significantly enhanced below the glass transition temperature (Tg), and Tg shifted to a higher temperature, with a maximum at a surfactant loading of 0.6 CEC. The mechanical properties, including tensile strength, flexural strength, flexural modulus and impact strength, increased and then decreased with surfactant loading, with the maximum observed also at a surfactant loading of 0.6 CEC. In conclusion, an ideal balance between thermal and mechanical properties can be obtained at a surfactant quantity equivalent to 0.6 times the clay CEC. Moreover, all the composites exhibited obvious improvement in thermal and mechanical properties as compared to those of neat PBS.     

Synthesis and characterization of Pt–Sn–Ce/MC ternary catalysts for ethanol oxidation in membraneless fuel cells

The present work represents the mesoporous carbon-supported Pt–Sn and Pt–Sn–Ce catalysts with different mass ratios have been prepared by co-impregnation reduction method. The prepared catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigation. The XRD patterns of prepared Pt/MC (100) Pt–Sn/MC (75:25), Pt–Ce/MC (75:25), and Pt–Sn–Ce/MC (75:20:05) catalysts showed that Pt metal was the predominant material in all the samples, with peaks attributed to the face-centered cubic (fcc) crystalline structures. Additionally changes in the lattice parameters observed for Pt suggest the incorporation of Sn into the Pt crystalling structure with the formation of an alloy mixture with the SnO₂ phase. The TEM analysis designates that the prepared catalysts had similar particle morphology, and their particle sizes were 2–5 nm. The electrochemical studies showed that ternary catalyst shows best performance for oxidation of ethanol molecule at normal temperature. The enhanced ethanol oxidation activity for the ternary Pt–Sn–Ce catalyst is mainly attributed to the synergistic effect of bifunctional mechanism with electronic effect. Additionally, chemical nature of ceria affords oxygen-containing molecule to oxidize acetaldehyde to acetic acid. In this present context, 1 M ethanol was used as a fuel, 0.1 M sodium perborate was used as an oxidant, and 0.5 M sulfuric acid was used as an electrolyte. In mesoporous carbon-supported binary Pt–Sn and ternary Pt–Sn–Ce anode catalysts were effectively tested in a single membraneless fuel cell at normal temperature. The presence of Sn and Ce enhances the CO oxidation; they produced an oxygen-containing species to oxidize acetaldehyde to acetic acid.     

Relationship between the structural and catalytic properties of mechanosynthesized lithiated manganese oxides

The relationship between the structural and catalytic properties of lithiated spinel manganese oxides was investigated by means of X-ray diffraction, Infrared and Xanes spectroscopies, thermogravimetric analysis, and by evaluating two catalytic oxidation tests, namely the carbon black combustion and the toluene conversion. Li-Mn-O catalysts were prepared from stoichiometric (Li₂O + MnO₂) mixtures, either by the classical high temperature ceramic method or by mechanochemistry. For both catalytic tests, some spectacular temperature reductions were measured as a function of grinding. A remarkable decrease of 210 °C (from 650 °C to 440 °C) in the carbon black combustion temperature was obtained when using mechanosynthesized Li-Mn-O spinel prepared from a mixture of Li₂O and MnO₂ ground for 3 hours, whereas a 100 % toluene conversion rate was achieved for a temperature lower than 200 °C for the 5 hours milled ceramic LiMn₂O₄ while the as-made ceramic was inactive. The enhancement of the performances (i.e. decrease in carbon black combustion temperature Tc and decrease in toluene conversion temperature T_95%) is due both to an increase in grain boundaries and in specific BET surface area and to the nano-crystallite size nature of the material. Besides, the spinel stoichiometry (both in oxygen or in cations) reflected by the lattice parameter variation plays a significant role in the catalytic reaction mechanism.     

Synthesis of nanostructured lean-NO x catalysts by direct laser deposition of monometallic Pt-, Rh- and bimetallic PtRh-nanoparticles on SiO2 support

Monometallic Pt and Rh and bimetallic PtRh catalysts with a highly dispersed noble metal weight loading of ca. 1 wt% were produced via the direct deposition of nanoparticles on different SiO₂ supports by means of pulsed ultra-violet (248 nm) excimer laser ablation of Pt, Rh bulk metal and PtRh alloy targets. Backscattered electron microscopy (BSE), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were employed to characterize the deposited nanoparticles, which were found to exhibit narrow size distribution centred around 2.5 nm. The catalytic activities for lean NO _x reduction of the monometallic and bimetallic catalyst samples were investigated in a flow reactor setup in the temperature range 100–400°C using a test gas mixture representative of oxygen rich diesel engine exhaust gas. For comparison a Rh/SiO₂ reference catalyst prepared by a conventional impregnation method was also tested. Further experiments were performed in which PtRh nanoparticles were deposited on a Rh/SiO₂ reference catalyst sample to study the possibility for controlled modification of its activity. The catalytic activity measurements revealed that among the samples solely prepared by laser deposition the PtRh–SiO₂ nanoparticle catalyst showed the highest activity for NO _x reduction at low temperatures 100–300°C. In addition, it could be demonstrated that the initially low NO _x reduction activity and the N₂ selectivity of the Rh/SiO₂ reference catalyst sample for temperatures below 250°C can be enhanced by post laser deposition of PtRh nanoparticles.     

Effect of Preparation Method on the SCR Activity of Fe-Doped CoCr Oxide Catalysts

Fe-doped CoCr oxide catalysts are prepared by solid-phase mixing method, coprecipitation method, mechanical mixing method, and citric acid method, respectively, and their catalytic activity in the selective catalytic reduction of nitrogen oxides with NH₃ (NH₃-SCR) is tested. The Fe_0.5CoCrO_x catalysts prepared by all preparation methods have good water resistance and sulfur resistance when the calcination temperature is 400 °C. Fe_0.5CoCrO_x prepared by coprecipitation method by calcination at 400 °C (CP-400) is shown to have the optimum catalyst activity. In addition, the catalysts are characterized by a series of characterizations. The characterization results show that CP-400 has the largest specific surface area, which makes the active and acidic sites highly dispersed on the surface of CP-400, resulting in stronger redox and acidity and improved SCR activity. The removal of NO by NH₃-SCR over CP-400 at 150 °C follows the Eley-Rideal (E R) and Langmuir-Hinshelwood (L H) mechanisms.     

Polycyanurate–Organically Modified Montmorillonite Nanocomposites: Structure–Dynamics–Properties Relationships

Polycyanurate‐modified montmorrilonite (PCN‐MMT) nanocomposites were synthesized by polymerization of dicyanate ester of bisphenol A in the presence of MMT dispersed by ultrasound. Techniques of IR spectroscopy, WAXD, and TEM were applied to study polymerization kinetics and structure of the nanocomposites prepared, whereas their dynamics and thermal/mechanical properties over the ?30 to 420°C range were studied by using DSC, laser‐interferometric creep rate spectroscopy (CRS), and dielectric relaxation spectroscopy (DRS) techniques. It was shown that a small amount of MMT additive acts as a catalyst of polymerization and results in the formation of complicated intercalated/exfoliated structures, as well as strongly modifies the dynamics in the PCN network. Pronounced dynamic heterogeneity was observed for PCN/MMT nanocomposites. Along with the main PCN glass transition, two new glass transitions, at much higher and much lower temperatures, were revealed as a consequence of constrained dynamics in matrix interfacial nanolayers and due to incomplete local cross‐linking in the PCN matrix, respectively. In addition, increased sub‐T _g mobility was observed in these nanocomposites. A two‐fold rise of modulus of elasticity as well as increasing thermal stability and arising microplasticity at low temperatures, promoting, obviously, improved crack resistance in a brittle PCN network, were found for the PCN‐MMT nanocomposites.     

沉淀方法及铈掺杂对铜锰氧化物催化剂催化氧化CO性能的影响

研究了铈掺杂及沉淀方法对铜锰氧化物催化剂的结构特性及室温催化氧化CO性能的影响. 使用X射线衍射、N₂吸附脱附、等离子体发射光谱、程序升温还原、紫外可见漫反射以及X射线光电子能谱等手段对各催化剂进行了表征. 发现掺杂少量的铈于铜锰氧化物催化剂中,CeO₂相高度分散并能阻止催化剂的烧结和团聚,所制得的催化剂的颗粒较小,氧化还原性能提高,比表面增大,并形成了较多的活性位点,使其对CO的催化氧化性能明显提高.     

Green preparation of Pd nanoparticles on SBA-15 via supercritical fluid deposition and application on Suzuki–Miyaura cross-coupling reaction

A well-dispersed green Pd/SBA-15 catalyst with an average size of 13.7 nm and 492.6 m²/g BET surface area is prepared via supercritical fluid deposition method with a new bipyridyl precursor that enables reduction at mild conditions at 80 °C and 17.2 MPa. The catalytic performance of Pd/SBA-15 prepared using scCO₂ with hydrogen reduction was assessed for Suzuki–Miyaura coupling reaction of bromobenzene and phenylboronic acid that was chosen as a model coupling reaction. The catalyst was tested in six different solutions and in three organic and inorganic bases during reactions. In general, the effect of bases is investigated when solvents are held constant and K₂CO₃ appears to have the best results in the activity studies used. For each of the 3 bases used, the highest catalytic activity was reached as the result of the solvent system being ethanol/water (1:1). The highest catalytic conversion was obtained in the ethanol-K₂CO₃ solvent-base pair. The catalyst synthesized in this study exhibited high activities and TON value was found as 160.8 at room temperature.     

Continuous catalytic pyrolysis of oily sludge using U-shape reactor for producing saturates-enriched light oil

Continuous catalytic pyrolysis of oily sludge was carried out in a special U-shape reactor for producing saturates-enriched light oil. The sludge underwent thermal pyrolysis first and then catalytic pyrolysis. During the thermal pyrolysis, chain hydrocarbons were first cracked and further polymerized into aromatics. The effect of temperatures (400–800 °C) on the products was investigated and the maximum liquid yield (67.7%) was obtained at 500 °C. High temperature promoted polymerization, thus the distribution of aromatics in the liquid product was increased and was more concentrated in polyaromatics at 800 °C. In the catalytic upgrading stage, dolomite was used as catalyst and aromatics were adsorbed on it, either aggregated or decomposed. As a result, a light oil product with 57.0% saturates was obtained at the residence time of 8.9?s due to the conversion of aromatics and heavy hydrocarbons into light aliphatic hydrocarbons such as straight chain hydrocarbons. Compared with the oil phase in the raw sludge sample, the content of saturates was increased by 45.0% and that of the asphaltenes was reduced by 88.5%. Meanwhile, the inherent moisture in the oily sludge could participate in the steam reforming reaction, promoting the decomposition of aromatics and leading to an increase in the H₂ generation. Moreover, the release of H₂S was reduced from 0.132 to 0.005?mol per kg sludge and the sulfur content of the oil product was also decreased in the presence of dolomite. The deactivation of dolomite can be attributed to the carbonization of CaO and deposition of polyaromatic coke on the catalyst surface.     

Effect of melt compounding temperature on dielectric relaxation and ionic conduction in PEO–NaClO<Subscript>4</Subscript>–MMT nanocomposite electrolytes

Polymer nanocomposite electrolytes (PNCEs) of poly(ethylene oxide) and sodium perchlorate monohydrate complexes with montmorillonite (MMT) clay up to 20 wt.% MMT concentration of poly(ethylene oxide) (PEO) are synthesized by melt compounding technique at melting temperature of PEO (∼70 °C) and NaClO₄ monohydrate (∼140 °C). Complex dielectric function, electric modulus, alternating current (ac) electrical conductivity, and impedance properties of these PNCEs films are investigated in the frequency range 20 Hz to 1 MHz at ambient temperature. The direct current conductivity of these materials was determined by fitting the frequency-dependent ac conductivity spectra to the Jonscher power law. The PNCEs films synthesized at melting temperature of NaClO₄ monohydrate have conductivity values lower than that of synthesized at PEO melting temperature. The complex impedance plane plots of these PNCEs films have a semicircular arc in upper frequency region corresponding to the bulk material properties and are followed by a spike in the lower frequency range owing to the electrode polarization phenomena. Relaxation times of electrode polarization and ionic conduction relaxation processes are determined from the frequency values corresponding to peaks in loss tangent and electric modulus loss spectra, respectively. A correlation is observed between the ionic conductivity and dielectric relaxation processes in the investigated PNCEs materials of varying MMT clay concentration. The scaled ac conductivity spectra of these PNCEs materials also obey the ac universality law.     

Dielectric properties and fluctuating relaxation processes of poly(methyl methacrylate) based polymeric nanocomposite electrolytes

Solid polymer nanocomposite electrolytes (SPNEs) consisted of poly(methyl methacrylate) (PMMA) and lithium perchlorate (LiClO₄) of molar ratio C=O:Li⁺=4:1 with varying concentration of montmorillonite (MMT) clay as nanofiller have been prepared by classical solution casting and high intensity ultrasonic assisted solution casting methods. The dielectric/electrical dispersion behaviour of these electrolytes was studied by dielectric relaxation spectroscopy at ambient temperature. The dielectric loss tangent and electric modulus spectra have been analyzed for relaxation processes corresponding to the side groups rotation and the segmental motion of PMMA chain, which confirm their fluctuating behaviour with the sample preparation methods and also with change of MMT concentration. The feasibility of these relaxation fluctuations has been explained using a transient complex structural model based on Lewis acid–base interactions. The low permittivity and moderate dc ionic conductivity at ambient temperature suggest the suitability of these electrolytes in fabrication of ion conducting electrochromic devices and lithium ion batteries. The amorphous behaviour and the exfoliated/intercalated MMT structures of these nanocomposite electrolytes were confirmed by X-ray diffraction measurements.     

在Ni/HZSM-5催化剂上低温水蒸汽重整生物油制氢

利用浸渍方法制备的Ni/HZSM-5催化剂在生物油低温水蒸汽重整合成中表现了较高的催化活性． 探讨了催化剂的组成、重整温度、水碳比例对重整过程的影响．在电催化重整研究中,发现催化剂上通过的电流可以显著地促进生物油水蒸汽重整．通过对不同负载量的Ni/HZSM-5催化剂和Ni₂₀/Al₂O₃催化剂的催化活性的比较,NiO在催化剂中负载量为20%(Ni₂₀/ZSM)时表现出了最高的催化活性; 即使在450 oC时, 在Ni₂₀/ZSM催化剂上也可以达到碳转化率接近完全, 氢气产率约为90%的效果． 利用XRD、ICP/AES、H₂-TPR、BET等表征手段对Ni/HZSM-5催化剂的形态和结构进行了表征.     

Preparation and characterization of hybrid nanoparticles based on chitosan and poly(methacryloylglycylglycine)

CeO₂–MnO _x composites possessing rod-like morphology (fixed mole proportion of Ce/Mn) were synthesized through hydrothermal method and chosen as supporters to load PdO nanoparticles (PdO/Ce _x Mn_1–x ). The size of loaded PdO nanoparticles is about 2 nm. The catalytic behaviors of supported catalysts were examined through the complete catalytic oxidation of benzene. The results illustrated that the activities of supported catalysts were enhanced greatly as compared to unsupported, and the completely conversion temperature of benzene was reduced to ca. 250 °C. The effect of noble metal species (PdO) addition on the catalytic property and crystal structure of composites was researched in detail. The data revealed that the interaction between PdO and supporter, and intrinsic properties of supporter resulted in the enhancement of catalytic abilities.