聚苯乙烯非均相催化加氢研究进展

随着国民经济发展和人民生活水平的不断提高,聚苯乙烯(PS)产品的多样化、专业化成为了市场竞争和用户需求的发展趋势。聚合物催化加氢工艺作为提高PS专用料性能的重要改性手段,近几年来已成为不饱和聚合物化学改性领域的研究热点。文中主要综述了国内外PS非均相催化加氢制备聚环己烷基乙烯(PCHE)体系中加氢工艺的改进、加氢催化剂的设计优化及反应机理研究的新进展。阐述了催化剂的结构设计、物化性能以及反应过程中传质扩散阻力等对PS加氢活性的影响,探讨了PS非均相催化加氢体系中的"Blocky"加氢机理,提出未来PS非均相加氢催化剂研究重点应该放在催化剂的结构设计上,既要保证聚合物分子与活性中心高接近性,又要实现在加氢体系中的传质扩散与催化剂载体上活性位点高分散的最佳平衡。同时,为进一步提高加氢催化剂的综合性能,需要加强对聚合物加氢反应机理和催化剂合成改性技术的基础性研究。

Synthesis of Ni_2P promoted trimetallic NiMoW/γ-Al_2O_3 catalysts for diesel oil hydrotreatment

The Ni2P promoted and γ-Al2O3 supported NiMoW sulfide catalyst consisting of 4 wt% Mo, 22 wt% W, 2 wt% Ni and 2.5 wt% Ni2P was synthesized by a co-impregnation method. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction （XRD）, diffuse reflectance infrared Fourier transform （DRIFT） spectroscopy, NH3 temperature-programmed desorption （NH3-TPD） and transmission electron microscopy （TEM）. The results showed that Ni2P, Ni, Mo and W species were highly dispersed over γ-Al2O3. The hydrodesulfurization （HDS） of dibenzothiophene （DBT） showed that the presence of Ni2P brought a strong promotional effect on the HDS activity, which was further confirmed by the HDS and hydrodenitrogenation （HDN） of diesel oil under industrial conditions. The enhancement in HDN activity and stability by Ni2P addition could be attributed more to the effect of new active sites of Ni2P than that of acidity modification. The as-prepared Ni2P-NiMoW/γ-Al2O3 catalyst showed better hydrotreating performance than NiMoW/γ-Al2O3 and commercial catalysts.

Redistributing Cu species in Cu-SSZ-13 zeolite as NH3-SCR catalyst via a simple ion-exchange

The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to control.Herein,we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a“natural environment”for adjusting Cu distribution precisely.By using this proposed strategy,a series of Cu-SSZ-13x zeolites with different Cu contents and distributions were obtained.It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+species and thus allows the redistribution of the Cu species.The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart.The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors(e.g.,crystallinity,chemical composition,and porous structure)is responsible for the improved NH3-SCR performance and SO_(2) and H_(2)O resistance.Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.

Surface plasmon resonance metal-coupled biomass carbon modified TiO_(2) nanorods for photoelectrochemical water splitting

Exploring efficient and stable photoanode materials is a necessary link to realize the practical application of solar-driven photoelectrochemical(PEC)water splitting.Hence,we prepared rutile TiO_(2) nanorods,with a width of 50 nm,which was growth in situ on carbon cloth(TiO_(2)@CC)by hydrothermal reaction.And then,Ag nanoparticles(NPs)and biomass N,S-C NPs were chosen for the additional modification of the fabricated TiO_(2) nanorods to produce broccoli-like Ag-N,S-C/TiO_(2)@CC nanocomposites.According to the result of ultraviolet-visible diffuse reflectance spectroscopy(UV-vis)and PEC water splitting performance tests,Ag-N,S-C/TiO_(2)@CC broadens the absorption region of TiO_(2)@CC from the ultraviolet region to the visible regio n.Under AM 1.5 G solar light irradiation,the photocurrent density of Ag-N,S-C/TiO_(2)@CC is 89.8μA·cm^(-2),which is 11.8 times higher than TiO_(2)@CC.Under visible light irradiation,the photocurrent density of Ag-N,S-C/TiO_(2)@CC reaches to 12.6μA·cm^(-2),which is 21.0 times higher than TiO_(2)@CC.Moreover,Ag-N,S-C/TiO_(2)@CC shows a photocurrent responses in full pH range.It can be found that Ag NPs and N,S-C NPs play key roles in broaden the absorption range of TiO_(2) nanorods to the visible light region and,promote the occurrence of PEC water oxidation reaction due to the surface plasmon resonance effect of Ag NPs and the synergistic effect of N,S-C NPs.The mechanism demonstrated that Ag-N,S-C/TiO_(2)@CC can separate the photogenerated electron-hole pairs effectively and transfer the photogenerated electrons to the photocathode(Pt plate)in time.This research provides a new strategy for exploration surface plasma metal coupled biomass carbon materials in the field of PEC water splitting.

Mesoporogen-free synthesis of hierarchical sodalite as a solid base catalyst from sub-molten salt-activated aluminosilicate

A rapid and environmentally friendly approach to synthesize hierarchical sodalite from natural aluminosilicate mineral without the involvement of any mesoporogen or post-synthesis treatment was developed.This strategy involves three important steps:the first is the depolymerization of an aluminosilicate mineral into highly reactive silicon and aluminum species with ideal meso-scale structures through activation of a sub-molten salt.The second step is the hydrolysis and condensation of the activated aluminosilicate mineral into zeolitic precursors that also have a meso-scale structure.The third is the rapid zeolitization of the zeolitic precursors through the reversed crystal growth route at room temperature and ambient pressure to form hierarchical sodalite.The physicochemical properties of the as-synthesized sodalite were systematically characterized,and the formation mechanism of the hierarchical pore structure was discussed.When used as a solid base catalyst for Knoevenagel condensation,the as-synthesized sodalite and its potassium ion-exchanged product with hierarchical micro-meso-macroporous structure both exhibited high catalytic activity and product selectivity.

Tuning of the active phase structure and hydrofining performance of alumina-supported tri-metallic WMoNi catalysts via phosphorus incorporation

The effects of phosphorus on the structure and hydrofining performance of tri-metallic WMoNi/Al2O3 catalysts prepared with W/Mo-based hybrid precursor nanocrystals were investigated. The incorporation of phosphorus weakened the metal-support interactions （MSIs） and facilitated the formation of more synergetic NiWMoS phases with higher stacks. Catalytic tests using a fluid catalytic cracking diesel fuel showed that the changes in the MSIs and the morphology of the active phases had a more positive effect on the hydrodenitrogenation activity than on the hydrodesulfurization activity. In contrast, when phosphorus was incorporated into a tri-metallic WMoNiP/Al2O3 catalyst prepared by a conventional incipient impregnation method, the MSIs decreased causing aggregation of the metal species which resulted in poorer hydrofining performance of the catalyst. These results show that incorporating phosphorus into a WMoNi/Al2O3 catalyst can finely tune the structure of the active phase to enhance the hydrogenation and hydrodenitrogenation activity of the resulting tri-metallic catalyst.

Reaction performance of fluidized bed catalytic reactor of Group C^(+)particles

Group C particles are often regarded as non-fluidizable but have proven to effectively fluidize with nanoparticle addition,which results in small bubbles and a high gas holdup in the dense phase during the experiments.Group C^(+)particles provide an increased surface area for gas-solid contact and improve the reaction performance,especially for gas-phase catalytic reactions.On the basis of a previous study of the ozone decomposition reaction using Group C^(+)particles,a two-phase model was used to evaluate the reactor contact efficiency,and was used to compare the partial oxidation performance of the n-butane to maleic anhydride reaction in fluidized-bed catalytic reactors of Group C^(+)and Group A particles.The reactor with Group C^(+)particles achieved a higher n-butane conversion and MAN yield compared with that using Group A particles,based on the identical catalyst quantity or on the same gas residence time.Therefore,the reactor with Group C^(+)particles can achieve the same reaction conversion and yield with fewer catalysts or a smaller reactor size,or both.Therefore,the fluidized bed catalytic reactor of Group C^(+)particles is expected to be of major significance in industrial processes,especially for gas-phase catalytic reactions.

Possibilities of synthesizing new proton-rich nuclei with 40≤Z≤60 using multinucleon transfer reactions

Multinucleon transfer reactions near the Coulomb barrier are investigated based on the improved dinuclear system(DNS)model,and the deexcitation process of primary fragments are described using the statistical model GEMINI++.The production cross sections of^(40,48)Ca+^(124)Sn and^(64)Ni+^(130)Te based on the DNS model+GEMINI++are calculated and compared with experimental data.The calculated results reproduce experimental data.The cross sections of fusion-evaporation,fragmentation,and multinucleon transfer reactions in the region are also provided in this paper.The results show that in the region,fusion-evaporation and fragmentation reactions have good results in the relatively proton-rich region,but in the extreme proton-deficient region,the MNT reaction is still promising for synthesizing proton-rich nuclei.