Research on New Silica Sol Matrix Used in Fluid Catalytic Cracking Reaction

A new silica sol binder was obtained by mixing the acid-modified aluminium sulfate and water glass. The effect of SiO2 concentration in sodium silicate, pH value and polymerization was investigated. The new silica sol binder, which possessed abundant pore volume and suitable acid amount, was an ideal component for preparing cracking catalyst. As a result, the corresponding catalyst comprising the new binder showed excellent performance. Compared with the reference sample, the liquefied petroleum gas(LPG) and propylene yield obtained over this catalyst increased by 3.49 and 1.20 percentage points, respectively. The perfect pore structure and suitable Lewis acid amount of new silica sol were the possible reason leading to its outstanding performance.

Research on Catalytic Cracking Performance Improvement of Waste FCC Catalyst by Magnesium Modification

In this study,the deactivation mechanism caused by high accessibility of strong acid sites for the waste FCC catalyst was proposed and verified for the first time.Based on the proposed deactivation mechanism,magnesium modification through magnesium chloride impregnation was employed for the regeneration of waste FCC catalyst.The regenerated waste FCC catalyst was characterized,with its heavy oil catalytic cracking performance tested.The characterization results indicated that,in comparison with the unmodified waste FCC catalyst,the acid sites strength of the regenerated waste FCC catalyst was weakened,with no prominent alterations of the total acid sites quantity and textural properties.The heavy oil catalytic cracking results suggested that the catalytic cracking performance of the regenerated waste FCC catalyst was greatly improved due to the suitable surface acidity of the sample.In contrast with the unmodified waste FCC catalyst,the gasoline yield over the regenerated waste FCC catalyst significantly increased by 3.04 percentage points,meanwhile the yield of dry gas,LPG,coke and bottoms obviously decreased by 0.36,0.81,1.28 and 0.87 percentage points,respectively,making the regenerated waste FCC catalyst serve as a partial substitute for the fresh FCC catalyst.Finally,the acid property change mechanism was discussed.

Preparation of Core-Shell Composite of Y@Mesoporous Alumina and Its Application in Heavy Oil Cracking

A well core-shell composite of Y@meso-Al with a mesoporous alumina shell and a Y zeolite core was synthesized. The mesoporous alumina shell has a wormhole-like structure with large mesopores. The prepared catalytic cracking catalyst using this composite has exhibited excellent catalytic performance for heavy oil cracking thanks to its favorable physicochemical properties, such as high surface area, large pore volume and outstanding acid sites accessibility for large molecules provided by the composite. In comparison with the reference catalyst using pure Y zeolite, the oil conversion achieved by the above-mentioned catalyst increased by 2.73 percentage points, while the heavy oil yield and coke yield decreased by 2.23 percentage points and 1.28 percentage points, respectively, with the light oil yield increasing by 2.27 percentage points.

Application of New Heavy Metals Resistant Porous Binder Material Used in Fluid Catalytic Cracking Reaction

A novel porous binder was obtained from acid-treated kaolin. This new binder possessed abundant meso/macropores, good hydrothermal stability and heavy metal resistance. The prepared catalyst using new binder featured low attrition index and large pore volume. The catalysts were contaminated with Ni, V, and tested in a fixed-fluidized bed reactor unit. In comparison with the reference sample, the oil conversion achieved by the above-mentioned catalyst increased by 3.50 percentage points, and heavy oil yield decreased by 2.86 percentage points, while the total liquid yield and light oil yield increased by 2.82 percentage points and 0.79 percentage points, respectively. The perfect pore structure, good hydrothermal stability and heavy metal resistant performance of new binder were the possible causes leading to its outstanding performance.

Ultra-deep adsorptive removal of thiophenic sulfur compounds from FCC gasoline over the specific active sites of CeHY zeolite

Adsorption desulfurization performance of Na Y,HY and Ce HY zeolites is evaluated in a miniature fixedbed flow by model gasoline containing with thiophene,tetrahydrothiophene,2-methylthiophene,benzothiophene or mixed sulfur compounds.The structural properties of adsorbents are characterized by XRD,N2-adsorption and XPS techniques.Adsorption desulfurization mechanisms of these sulfur compounds over the specific active sites of adsorbents as a major focus of this work,have been systematically investigated by using in situ FT-IR spectroscopy with single and double probing molecules.Desulfurization experimental results show that the Ce HY adsorbent exhibits superior adsorption sulfur capacity at breakthrough point of zero sulfur for ultra-deep removal of each thiophenic sulfur compound,especially in the capture of aromatic 2-methylthiophene(about ca.28.6 mgS/gadsorbent).The results of in situ FT-IR with single probing molecule demonstrate an important finding that high oligomerization ability of thiophene or 2-methylthiophene on the CeHY can promote the breakthrough adsorption sulfur capacity,mainly resulting from the synergy between Br?nsted acid sites and Ce(III)hydroxylated species active sites located in the supercages of Ce HY.Meanwhile,the result of in situ FT-IR with double probing molecules further reveals the essence of oligomerization reactions of thiophene and 2-methylthiophene molecules on those specific active sites.By contrast,the oligomerization reaction of benzothiophene molecules on the active sites of Ce HY cannot occur due to the restriction of cavity size of supercages,but they can be adsorbed on the Br?nsted acid sites via protonation,and on Ce(III)hydroxylated species and extra-framework aluminum hydroxyls species via direct"S-M"bonding interaction.As to the tetrahydrothiophene,adsorption mechanism is similar to that of benzothiophene,except in the absence of protonation.The paper can provide a new design idea of specific adsorption active sites in excellent desulfurization adsorbents for elevating higher quality of FCC gasoline in the future.

Coordinative chain transfer copolymerization of 1,3-butadiene and isoprene by neodymium precatalyst

Coordinative chain transfer polymerization(CCTP)is a newly developed strategy that features similarly,but superiorly,to classical living polymerization,in other words,precise molecular weight controlling,narrow molecular weight distribution,atom economy and so on,and has been quickly grown as a powerful tool to prepare the target polymer materials[1].As an extension of this concept,the present study discloses our recent progresses on CCTP of butadiene(Bd)and isoprene(Ip)to prepare precisely controlled Bd/Ip copolymers.

Effect of LaPO_(4) Introduction as a Vanadium Trap for Preventing USY Zeolite Destruction

The use of lanthanum phosphate as a vanadium trap for preventing destruction of USY zeolite was studied.The effect of deposited vanadium on the hydrothermal destruction of zeolite was investigated by the solid-state NMR technique.LaPO4 species can inhibit the zeolite framework structure from being collapsed by vanadium after steaming treatment.The EPR results show the oxidation-reduction reaction in LaPO4 and V2O5 system and inhibition of zeolite destruction by V5+.The catalysts prepared from USY and LaPO-USY zeolites were also tested in the catalytic reactions of heavy oil.The assessment results indicated that the USY modified with LaPO4 could bring about remarkably high dehydrogenation ability.

Isobaric Vapor–Liquid Equilibrium for tert-Butyl Alcohol + Water + Propane-1,3-Diol + 1-Ethyl-3-Methylimidazolium Chloride at 101.3 kPa

In this study, we used a mixture of organic liquid propane-1,3-diol and ionic liquid 1-ethyl-3-methylimidazolium chloride([emim]Cl) as the entrainer to separate tert-butyl alcohol(TBA) + water. We measured the isobaric vapor–liquid equilibrium(VLE) for the quaternary system TBA + water + propane-1,3-diol + [emim]Cl at 101.3 kPa, and found the VLE data to be well correlated with the nonrandom two-liquid model. These results show that the mixed solvent of propane-1,3-diol + [emim]Cl can increase the relative volatility of TBA to water and break the azeotropic point. We found no notable synergetic effect between them, and observed that the liquid mixed solvent of propane-1,3-diol and [emim]Cl had lower viscosity than [emim]Cl, which makes it a promising entrainer for separating the TBA + water azeotrope in industrial applications.

Significantly Enhanced Melt Memory Effect of Metallocene-made Isotactic Polypropylene Containing Talc

The melt memory effect is a widely observed phenomenon in semi-crystalline polymers. In practical applications, various additives are usually introduced into polymers, which may affect their melt memory behavior. In this work, the effect of talc on the melt memory effect of metallocene-made isotactic polypropylene(M-PP) was investigated in detail by using the differential scanning calorimetry. The results indicated that the introduction of talc significantly strengthened the melt memory effect of M-PP. Specifically, the upper limit temperature of Domain II increased from 161 ℃ to 174 ℃, resulting in a substantial widening of the temperature range of Domain IIa from 1 ℃ to 14 ℃. Analysis of the crystal orientation of the M-PP containing talc cooled from various Ts suggested that the remarkably enhanced melt memory effect could be ascribed to the stabilization of oriented nuclei facilitated by talc. This stabilizing effect was likely attributable to the prefreezing effect or the sorption interaction between talc and the M-PP chains.

Fe/N co-doped nano-TiO_(2)wrapped mesoporous carbon spheres for synergetically enhanced adsorption and photocatalysis

Carbon-based adsorption and TiO_(2)-based photocatalysis are both safe and low-cost ways of pollutant pu-rification.Constructing C-TiO_(2)architectures can effectively improve removal efficiency.However,most of those carbon frames only acted as supporting substrates,exhibiting rather limited synergistic action from TiO_(2)and carbon.Herein,Fe/N co-doped nano-TiO_(2)wrapped on mesoporous carbon spheres with a core-shell structure was designed.The Fe,N co-doped carbon sphere with a hierarchical structure im-proved the synergy of adsorption and transfer during the photocatalytic process.Without extra dopant,the Fe and N partly exposed on the surface realized the in-situ migrating into the TiO_(2)shell to en-hance the interface effect,which significantly promoted the photocatalytic efficiency of the composite.Furthermore,the photocatalytic efficiency of the composite was investigated through two typical pollu-tants under visible-light irradiation.The degradation efficiencies for rhodamine B and paraxylene were 96.2%in 60 min and 94.1%in 20 min,respectively,with the apparent rate constant of 0.045 min^(-1)and 0.049 min^(-1),8.3 and 11.4 times of that for bare TiO_(2).The composite is likely advantageous for treating diverse environmental pollutants.

Zeolite-encaged Ultrasmall Pt-Zn Species with Trace Amount of Pt for Efficient Propane Dehydrogenation

Propane dehydrogenation(PDH)has become a globe-welcoming technology to meet the massive demand for propylene,but the most commonly used Pt-based catalysts suffer from quick sintering,poor selectivity for propylene,and unsatisfied Pt utilization.Herein,a series of Silicalite-1(S-1)zeolite-encaged ultrasmall Pt-Zn clusters with a trace amount of Pt[40—180 ppm(parts per million)]were developed by using a one-pot ligand-protected direct H_(2) reduction method.Interestingly,the extremely low amount of Pt can significantly promote the activity of zeolite-encaged Zn catalysts in PDH reactions.Thanks to the high Pt dispersion,the synergy between Pt and Zn species,and the confinement effect of zeolites,the optimized PtZn@S-1 catalyst with 180 ppm Pt and 1.88%(mass fraction)Zn,exhibited an extraordinarily high propane conversion(33.9%)and propylene selectivity(99.5%)at 550℃with a weight hourly space velocity(WHSV)of 8 h^(-1),affording an extremely high propylene formation rate of 340.7 mol_(C_(3)H_(6))·g_(Pt^(-1))·h^(-1).This work provides a reference for the preparation of zeolite-encaged metal catalysts with high activity and noble metal utilization in PDH reactions.

Thermostable α-Diimine Nickel Complexes with Substituents on Acenaphthequinone-backbone for Ethylene Polymerization

In order to promote the thermostability of a-diimine nickel complex by ligand backbone structure,a series of α-diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization.When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone,the thermal stability and activity of the catalyst could be significantly improved.The catalytic activity of complex C2[5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-diisopropyl)acenaphthylene-1,2-diimine]nickel(Ⅱ)dibromide with isopropyl substituents on N-aryl reached 8.2×10^6g/(molNi·h)at 70℃and 2 MPa.The activity of[5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(Ⅱ)dibromide(C3)still maintained at 6.7×10^5 g/(molNi·h)at 120℃.Compared with C3 containing bulky dibenzhydryl substituents,the activity of C2 was sensitive to the change of the polymerization pressure.However,the polyethylenes obtained from complex C3 had lower branching density.Meanwhile,the molecular weight could reach 971 kg/mol,which is almost 5 times as much as that of the polyethylene obtained from complex C2.