Lin Hua Zhu

Isomerization of α-Pinene over Alumina-Pillared Montmorillonite

In this work, the liquid phase catalytic isomerization of α-pinene over alumina-pillared montmorillonitewas investigated, and the influence of reaction temperature, reaction time and amount of the catalyston the conversion of α-pinenewere discussed systematically, and the optimum reaction conditions forisomerization of α-pineneover alumina-pillared montmorillonitewere obtained. The basal spacing of thealumina-pillared montmorillonite was characterized by X-ray diffraction, and the liquid reactant was separated and identified by gas chromatography. The result showed that alumina-pillared montmorillonite with 1.83nm of basal spacing exhibited a high catalytic activity for the isomerization of α-pinene, and 97.4% conversion of α-pinene was achievedat 373K for 3hwhen the mass ratio of catalyst to α-pinene was 1/10.

Comparision of the Preparation Methods of Mesoporous Phosphate Compounds Belonging to NZP Family

Using polyethylene oxide (PEO) as template, the new types of mesoporous phosphate compound which belongs to NaZr2(PO4)3(NZP) family were synthesized by copreciptate, sol-gel and mechanochemical activation(MA) route respectively. The physical phase and pore structure of the synthesized powder materials were characterized by X-ray diffraction (XRD) and N2 adsorption–desorption. The results showed that the crystalline NZP family compound with mesoporous structure is formed by sol-gel route followed with calcination as well as MA method followed with hydrothermal treatment when the mole ratio of PEO to Zr is 1:10, and the specific surface area, average pore diameter and pore volume of the synthesized powder is 20-50m2/g, 3-6.nm and 0.05-0.12cm3/g respectively. The above research results indicate that it is promising to expand the application field of the powder of NZP family from low thermal expansion ceramics to catalytic materials.

Study on the Properties of Fe3+ Sorption to SrZr4(PO4)6 Materials

SrZr4(PO4)6 (SZP) materials were synthesized by precipitate method and dispersed by small molecular solvent. The properties of adsorption materials SZP to Fe3+ have been examined. The equilibrium adsorption indicated that the adsorption equilibrium time of SZP to Fe3+ was 16h at room temperature, and the equilibrium adsorption capacity was 0.318~0.924mg Fe3+/gSZP. The adsorption capacity of 60°C is less than 20°C’s. In addition, the optimum dosage of the SZP adsorbent was 3g , and the corresponding adsorption ratio is 50% .

Intercalation of Gold Nanoparticles into Na-Montmorillonite

Several type of gold precursors including pre-synthesized Au (en)2Cl3 and gold colloid were tried to intercalate into the layer space of Na-Montmorillonite (Na-MMT). In the preparation, DDA and PAA were employed to cap the pre-synthesized gold colloidal particles and then intercalated into Na-MMT, and the Au (en)2Cl3 was directly intercalated to Na-MMT through cation exchange. X-ray diffraction (XRD), fluorescence analysis (XRF) and transmission electron microscopy (TEM) were used to characterize the prepared samples. The results showed that the gold colloid modified by dodecylamine (DDA) and polyallylamine hydrochloride (PAA) respectively were successfully intercalated into the layer gallery of Na-MMT based on the mechanism of covalent capture. However, thermal treatment at 773K for 2h resulted in migration of gold nanoparticles from layer space to the out surface of the Na-MMT.

The Influence of Different Preparation Methods on the Activity for CO Oxidation on the LDHs-Supported Gold Catalysts

Au nanoparticles supported on MgAl-LDHs has been synthesized by coprecipitation method, gold colloid routs as well as intercalation and assembly method respectively. The influence of the above different preparation methods on the activity of the gold catalysts for CO oxidation was investigated, and the phase and gold particle size distribution of the catalysts were analyzed by XRD and TEM respectively. The results show that 100% conversion of CO on the fresh prepared gold catalysts synthesized by gold colloid routs and intercalation assembly method can be achieved at room temperature when the catalysts were activated at 473K for 2h in the air. The gold particle size distribution was range from 2nm to 7nm.

The Factors which Influence on the Physical Phase of Phosphate Compounds Belonging to NZP Family

A new type of phosphate compound with different chemical composition but the same framework belonging to NaZr2(PO4)3(NZP) family were synthesized by chelating sol-gel route. The factor that influence on the physical phase was investigated in this paper. The physical phase and pore structure of the synthesized powder materials were characterized by X-ray diffraction (XRD) and N2 adsorptiondesorption respectively. The results showed that the crystalline NZP family compounds CaZr4(PO4)6 and KZr2(PO4)3 which is occupied by Ca2+ and K+ respectively at lattice site of MIcan be prepared by sol-gel route followed with calcinations at 700-800°C for 2h, but when the gel precursor of CaZr4(PO4)6 was treated by hydrothermal crystallization at 160°C for 24h, the obtained powder was NH4Zr2(PO4)3 instead of CaZr4(PO4)6.

Influence of Synthetic Methods on the Acid Catalytic Activity of NZP Family Compounds Modified by Doping Aluminum

A new type of NZP family compound CaZr4(PO4)6 was synthesized by sol-gel method and coprecipitation method respectively, and the acidity of CaZr4(PO4)6 was modulated by doping aluminum. The phase and pore structure of the samples were characterized by X-ray diffraction (XRD) and N2 adsorption-desorption, the acid catalytic activity of CaZr4(PO4)6 doped by Al were investigated by using alpha-pinene isomerization as probe reaction. The results show that CaZr4(PO4)6 doped with Al element synthesized by sol-gel method have regular mesoporous structure and weak strength acid site, therefore the catalytic activity on these samples for alpha-pinene isomerization is higher than that on the Al doping samples prepared by coprecipitation method.

Modification of Mesoporous CaZr4(PO4)6 and its Acid Catalytic Performance

A series of new type acid catalyst samples based on mesoporous CaZr4(PO4)6(CZP) belonging to NZP family synthesized by sol-gel method was obtained by Al, La, B incorporation in CZP or by heteropoly acid H3PW12O7•xH2O(HPW) loading on CZP, and their acid catalytic activity and selectivity were investigated by using α-pinene isomerization as a probe reaction. The phase, pore structure and surface acidity of the catalyst samples were characterized by X-ray diffraction (XRD), N2 sorption and NH3 temperature programmed desorption (NH3-TPD) respectively. The results showed that the surface acidity of CZP modified by elements incorporation and HPW loading was improved in a different extent. The conversion of α-pinene at 150 °C reached to 41 % over the catalyst sample noted as Al-CZP-0.15 in which the mole ratio of Al to Zr was 0.15. Under the same reaction conditions, the conversion of α-pinene was above 95 % over the CZP supported with 20-30wt. %HPW.

Preparation of Layered Double Hydroxide (LDHs)-Supported Gold Catalysts and its Activity and Stability for Low-Temperature CO Oxidation

A new type of gold catalysts have been prepared by supporting gold colloids on layered double hydroxide (MgAl-LDHs) carrier at different pH values. CO oxidation reaction at room temperature was used as probe reaction to test the oxidation activity of the gold catalysts, and X-ray diffraction (XRD), X-ray fluorescence (XRF) and high resolution transmission election microscopy (HRTEM) techniques were used to characterize the physical phase, gold loading, morphology as well as mean diameter of gold particles and particle distribution of the represented gold catalyst samples. Influence of pH value during synthesis of the catalysts on the gold loading and oxidation activity of the gold catalysts was studied. Besides these, the stability of the gold catalysts was investigated by thermal treatment and exposure to air and natural light for a long time. The results indicated that gold colloids can be attached on the carrier easily when pH value was controlled between 6-7, and gold loading in the gold catalysts prepared in this condition was above 1.3wt.%. 100% conversion of CO at room temperature can be obtained when the fresh prepared catalysts had been calcined in the air for 2 h at 473 K. The HRTEM images of the gold catalyst showed that the gold particles were highly dispersed on the surface of the carrier, and the average size of the gold particles was 3.2 nm. After thermal treatment at 723 K or storage 4 weeks in air, gold particle size was still kept less than 5nm and the conversion of CO at room temperature over the aged catalysts achieved 100%.