Application of Acid Modified Catalysts with Different SiO_(2) Contents in the Hydrocracking of Light Cycle Oil for Light Aromatics Production

A series of functionalized USY/SiO_(2) zeolite composite supports were synthesized using the coating coprecipitation method,with tetraethyl orthosilicate(TEOS)as the silicon source and different ratios of USY to TEOS.Active metals nickel(Ni)and molybdenum(Mo)were loaded onto the supports using the impregnation method.Finally,a series of hydrogenation catalysts were synthesized.The characterization results showed that,compared with the USY catalyst,the addition of a certain quantity of SiO_(2) resulted in the disappearance of the strong acid sites on the catalyst,the number of weak acid and medium strong acid sites decreased,and a certain number of secondary mesoporous structures were formed.The addition of SiO_(2) reduced the secondary cracking of benzene,toluene,xylene,and ethylbenzene(BTXE)effectively,while excessive amounts of SiO_(2) reduced the hydrogenation activity of the catalyst,leading to a decline in the final yield of BTXE.At a maximum SiO_(2) content of 45%,the hydrogenation depth of light cycle oil(LCO)reached an optimum value.The hydrogenation performance of LCO was investigated in a fixed bed reactor at 380℃,4 MPa,and H2/oil volume ratio of 800:1,where the gasoline and diesel fractions reached 80.00%and 16.74%,respectively.NiMo-YS45 had the highest BTXE selectivity,and the final yield of BTXE reached 21.27%.

Effect of preparation methods on the hydrocracking performance of NiMo/Al_(2)O_(3) catalysts

In this work,NiMo catalysts with various contents of MoO_(3)were prepared through incipient wetness impregnation by a twostep method(NMxA)and onepot method(NMxB).The catalysts were then characterized by XRD,XPS,NH3TPD,H_(2)TPR,HRTEM,and N_(2)adsorptiondesorption technologies.The performance of the NiMo/Al_(2)O_(3) catalysts was investigated by hydrocracking lowtemperature coal tar.When the MoO3 content was 15 wt%,the interaction between Ni species and Al_(2)O_(3) on the NM15B catalyst was stronger than that on the NM15A catalyst,resulting in the poor performance of the former.When the MoO^(3) content was 20 wt%,MoO_(3) agglomerated on the surface of the NM20A catalyst,leading to decreased number of active sites and specific surface area and reduced catalytic performance.The increase in the number of MoS_(2) stack layers strengthened the interaction between Ni and Mo species of the NM20B catalyst and consequently improved its catalytic performance.When the MoO_(3) content reached 25 wt%,the active metals agglomerated on the surface of the NiMo catalysts,thereby directly decreasing the number of active sites.In conclusion,the twostep method is suitable for preparing catalysts with large pore diameter and low MoO_(3) content loading,and the onepot method is more appropriate for preparing catalysts with large specific surface area and high MoO_(3) content.Moreover,the NMxA catalysts had larger average pore diameter than the NMxB catalysts and exhibited improved desulfurization performance.

Hydrocracking of Low-Temperature Coal Tar over CoMo Catalysts Supported on ZrO2-Al2O3 Composite Oxides

A series of CoMo/ZrO2-Al2O3 catalysts with different contents of ZrO2 were prepared and characterized through XRD,XPS,NH3-TPD,H2-TPR,HR-TEM,and N2 adsorption-desorption technologies.The performance of the catalysts for low-temperature coal tar(LTCT)hydrocracking reaction was investigated.The interaction between active metals and Al2O3 was weakened with the introduction of ZrO2,which increased the MoS2 content and the stack layer number of MoS2 slabs to further promote the catalytic performance.At the same time,the amount of acid sites increased with an increasing ZrO2 content.When the ZrO2 content reached 32%,the pore volume of the catalyst decreased significantly.This phenomenon reduced the content of MoS2 and the stack layer number of MoS2 slabs,which were not conducive to improving the catalytic performance.The catalyst containing 24%of ZrO2 exhibited the best catalytic performance for hydrocracking reaction,with the residue conversion and the total yield of gasoline and diesel fractions reaching 60.64%and 66.54%,respectively,which could fulfill the requirements for hydrocracking LTCT.

Recent advances of inorganic phosphates with UV/DUV cutoff edge and large second harmonic response

Phosphates are important candidates for ultraviolet/deep-ultraviolet(UV/DUV)nonlinear optical(NLO)materials by good transparency ability and variability of anion species as well as different coordinated cations.Phosphates have been reported as minerals or NLO materials with abundant condensed anionic framework.For phosphate-based NLO materials,how to improve the second harmonic generation(SHG)response and birefringence re-mains a great challenge.Herein,this review analyzes the structure-property relationship of the representative UV/DUV phosphates,and the microscopic mechanism to achieve a balance between the short absorption edge and large SHG response is summarized.It provides a new idea to study the UV/DUV phosphate NLO materials.

Improved thermal conductivity of epoxy resin by graphene-nickel three-dimensional filler

Owing to high thermal conductivity,carbon nanotube and graphene have been used as nanofillers to improve the thermal conductivity of polymer.However,the agglomeration of nanofillers in polymer inhibits their applications in improving the thermal conductivity of composite.To overcome this problem,graphene was grown on Ni foam by chemical vapor deposition in this work.And graphene-nickel three-dimensional filler was added into epoxy resin to improve the thermal conductivity of epoxy resin.Ni foam can prevent the agglomeration of graphene in epoxy resin and a thermally conductive network by graphene and Ni foam was formed in epoxy resin.By adding graphene-nickel three-dimensional filler into epoxy resin,the thermal conductivity of graphene-nickel/epoxy composite can reach up to 2.6549 W⋅m^(-1)⋅k^(-1),which was 9 times higher than that of raw epoxy resin.

Cetyltrimethylammonium chloride(CTAC)catalyzed one-pot synthesis of novel coumarin-4H-pyran conjugates in aqueous media

Novel fluorescent coumarin-4H-pyran conjugates were achieved by three-component reactions of various synthetic β-ketoesters with aldehydes and malononitrile in aqueous media.Besides mild reaction conditions,operational simplicity,absence of tedious separation procedures,using of inexpensive and nontoxic commercially available cationic surfactant cetyltrimethylammonium chloride（CTAC） as a catalyst are the prominent advantage of this method.

Enhanced Salt Tolerance of Polyurethane Based Multilayer Films

In our previous study,polyurethane(PU)based multilayer films assembled with weak polyelectrolytes exhibited controllable loading and release properties,but would be decomposed in high salt solution.Herein,a strong polyelectrolyte,poly(styrene sulfonic acid)sodium(PSS),was introduced to fabricate multilayer films.The salt tolerance of the film was investigated by evaluating the loading and release profiles towards model drug in salt solution with different concentrations.Results showed that the release behavior of the film,as well as its loading capacity,can be tuned by varying the salt concentrations.And the film showed a good salt tolerance that can remain integrity even after 6 cycles of drug loading and release in 600 mmol•L^(−1) NaCl solution.It showed that the salt tolerance of PU based films can be greatly improved through assembling with strong polyelectrolyte.