Synthesis of ZSM-22/SAPO-11 composite molecular sieve-based catalysts with small crystallites and superior n-alkane hydroisomerization performance

To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).

Synthesis of hierarchical SAPO-11-based catalysts with Al-based metal-organic framework derivative as mesoporogen to improve n-decane branched isomerization

Hierarchical SAPO-11 molecular sieve(ACS-11) was successfully synthesized employing the Al2O3/carbon(Al_(2)O_(3)/C) composite obtained through the pyrolysis of Al-based metal-organic framework(Al-MOF-96)as mesoporogen.Unlike other carbon-based mesoporogens with strong hydrophobicity,the Al_(2)O_(3)/C interacts with phosphoric acid and generates the AlPO_(4)/C structure,which promotes the Al2O3/C dispersion in the synthesis gel of SAPO-11 and avoids the phase separation between them.The Al_(2)O_(3)/C as mesoporogen decreases the crystallite size of SAPO-11 via preventing the aggregation of SAPO-11crystals.Additionally,the addition of Al_(2)O_(3)/C improves the Si distribution in the ACS-11 framework.Consequently,ACS-11 has smaller crystallites,more mesopores,and a greater amount of medium Bronsted acid centers than the conventional microporous SAPO-11 and the SAPO-11 synthesized using activated carbon as mesoporogen.The corresponding Pt/ACS-11 catalyst exhibits the maximal selectivity to multi-branched C10isomers(23.28%) and the minimal cracking selectivity(15.83%) in n-decane hydroisomerization among these catalysts.This research provides a new approach for preparing hierarchical silicoaluminophosphate molecular sieve-based catalysts to produce high-quality fuels.

n-Nonane hydroisomerization over hierarchical SAPO-11-based catalysts with sodium dodecylbenzene sulfonate as a dispersant

To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.

Quinoxaline-based Polymers with Asymmetric Aromatic Side Chain Enables 16.27% Efficiency for Organic Solar Cells

In recent years, due to the rapid development of high-performance small molecule acceptor (SMA) materials, the researches on p-type electron donor materials for matching with current efficient SMAs have become important. By means of asymmetric strategies to optimize the energy levels and inter/intramolecular interactions of molecules, we designed and synthesized an asymmetric aromatic side chain quinoxaline-based polymer donor TPQ-0F. Meanwhile, we took advantage of F atom which could form noncovalent interaction and strong electron-withdrawing property, to obtain the optimized quinoxaline-based polymer donors TPQ-1F, TPQ-1Fi and TPQ-2F. Eventually, the binary device based on TPQ-2F achieved an efficient power conversion efficiency (PCE) of 16.27%, which attributed to balanced hole/electron mobilities, less charge carrier recombination, and more favorable aggregation morphology. Our work demonstrates the great potential of asymmetric aromatic side chain quinoxaline-based polymer donors on optimizing the morphology of blending films, improving inter/intramolecular interactions, and subtly tuning energy level, finally for more efficient organic solar cells.