Pseudo-boehmite hollow microspheres(PBHMS)which possess the advantages of high specific surface area,large pore volumes and low density are widely used as adsorbent and catalyst carrier.Recently,the controllable preparation of hollow microspheres via low-cost and simple methods have been widely studied.The preparation methods for hollow microspheres are mainly comprised of template method and template-free method.For template method,the size and shape for preparation of hollow microspheres can be accurately controlled by the template,but the they generally require multistep processes to remove templates in product via calcination or etching.Compared with the template method,the template-free method is simplicity of operator,but the type for preparation of hollow microspheres is limited.Based on above circumstances,PBHMS were prepared via mild templat-free hydrothermal method using budget aluminium sulfate and amides as raw materials.The main research contents are summarized as follow:(1)PBHMS with highly effective adsorption performance for CR were prepared via mlid template-free hydrothermal method at 180°C using budget aluminium sulfate and amides as raw materials and N,N-Dimethylformamide(DMF)as precipitant.Effects of dosages,hydrolysates of DMF,amides species including DMF,N-methylformamide(MF)and formamide(FA),and reaction times on the physicochemical properties of the pseudo-boehmite(PB)were studied in detail.It was found that increase on their crystallinity and shell thickness resulted from the different hydrolysis rate of the amides.The morphology and crystallinity of the obtained product were affected by hydrothermal time.Amorphous alumina hydrate,pseudo-boehmite core shell structure(PBCSS)and PBHMS were obtained at hydrothermal times of 60,140 and 360 min,respectively.Especially,DMA as a hydrolysate of DMF,can regulate the morphology of microspheres together with the sulfate ions,and make their pore sizes distribution centering at 3-4 nm.Importantly,the PBHMS prepared by using DMF as precipitant DMF:Al3+=6(molar ration)and hydrothermal time at 360 min showed the maximum adsorption capacity of 846.4 mg/g for CR calculated from Langmuir isotherm model,and its adsorption amount reached a high value of 476.1 mg/g at 60min due to the mentioned pore size distribution and high surface area of PBHMS(221.3m2/g).This template-free hydrothermal method using DMF as precipitant provides an alternative approach for preparing hydrated alumina for environmental applications.(2)Based on the fact that the PB possess the high surface acidity,the strong interaction between noble meta and PB resulted in the toxicosis of catalyst.Based on the PBHMS preparated in the chapter two,nitrogen(N)-doped pseudo-boehmite@C composites(CCB)were prepared by novel vapour-phase hydrothermal method using budget sucrose as C source and urea as N source to improve the surface properties of PB.The Pd/CCB were generated by impregnation method using Na Pd Cl4 solution.The results showed that CCB still retain similar phase structure,morphology and texture properties of PB(base).The dosage of sucrose and urea can determine the content of C and N in CCB,which can control the actual loading capacity(0.64-1.50%),particle size(3.85-6.02 nm)and dispersity(18.6-33.8%)of the Pd NP.These-OH,C,N atoms generated on the surface of CCB due to the introduction of C and N are beneficial to anchor and stabilize Pd NP in suit.In this study,no excess reductant and capping reagents were required,and it is a clean,simple and green method for the preparation of Pd/CCB catalyst.The hydrogenation efficiency of Pd/CCB(11.18 g/L)increased28.8%than the traditional Pd/PB(8.68 g/L).This cheap vapour-phase hydrothermal method provides an alternative approach for preparing high-performance catalyst in hydrogenation field. |