At present, most of the catalysts used for heterogeneous hydrogenation of nitrile butadiene rubber (NBR) are noble metal catalysts, which require high metal loading but low metal utilization and face challenges in recovery, leading to significant resource waste. The steric hindrance imposed by the large polymer molecules renders the hydrogenation of unsaturated C=C bonds in the backbone particularly challenging, and the degree of hydrogenation is low. In this experiment, Pd-Ni bimetallic nanocatalyst was prepared by co-impregnation method. The catalyst has uniformly distributed catalytic site and high selectivity for C=C bond hydrogenation and achieved a hydrogenation degree of 96% under optimized reaction conditions. The electronic state of Pd is modulated by Ni, enhancing hydrogen activation and catalytic activity. This study provides a novel strategy for developing NBR hydrogenation catalysts, which is significant for the large-scale production of high-value-added HNBR.

Adamantane-based high energy density fuels (HEDFs) play a key role in military and aerospace applications due to their high volumetric calorific value and high density. In the preparation of adamantane-based HEDFs by hydroisomerization of polycyclic aromatic hydrocarbons (PAHs) in coal tar, there is competition between cracking and ring-opening reactions. Therefore, USY zeolites were etched with NaOH solution to expand the mesoporous and regulate the acidity, inhibit the cracking reaction, and promote the ring-shift isomerization of perhydrophenanthrene (PHP) to alkyl-adamantane (AlA), increasing the yield of AlA from 19% to 32%. There are two processes in the conversion of PAHs to AlA, hydrogenation and ring-shift isomerization. Phenanthrene was first hydrogenated to PHP, then isomerized to alkyl-adamantane, the product distribution of alkyl-adamantanes with different side chains was discovered, part of the C14 alkyl-adamantanes cracked, and the hydro-isomerization reaction of PHP occurred only on the outer surface or pore mouth of USY zeolite. It provides a new perspective for the hydroconversion of PAHs to HEDFs.

Nowadays, the rational design of high-performance catalysts with desirable resistance to metal leaching has become the principal challenge in the hydrogenation of nitrile butadiene rubber. In the present work, the Pd-Pt bimetallic alloy nanocatalyst exhibits an outstanding hydrogenation degree of 99.0%, obviously higher than that of the conventional monometallic Pd/SiO2 catalyst with the same Pd content (92.9%), accompanied by approximately 100% selectivity to C=C bonds. The results reveal that electron transfer from Pt to Pd confirms that the Pd species are in a rich-electron state, which boosts hydrogen activation and improves catalytic activity. Additionally, the incorporation of inactive Pt species promotes the formation of uniformly dispersed Pd-Pt alloy nanoparticles. The incorporation of inactive Pt species can enhance the metal-support interaction, reducing the residual metal content in hydrogenated nitrile butadiene rubber. The current research demonstrates a simple procedure for designing efficient bimetallic catalysts for the hydrogenation of unsaturated elastomer.

Hydroisomerization has been considered as an effective and efficient route for production of transportation fuels and lubricants with superior cold-flow properties. In current work, n-hexadecane (n-C16) hydroisomerization was investigated over Pt catalysts supported on hierarchical ZSM-48, which was post-treated by multi-step procedures including alkaline-acid, acid-alkaline-acid, steaming-alkaline-acid, and fluorination-alkaline-acid leaching. This work was purposed to construct the secondary mesoporous network, enhance the accessible acid sites in hierarchical ZSM-48 zeolite, and investigate their cooperative effects on hydroisomerization performance. The results demonstrated that the microporosity and the crystallinity were preserved after the controllable leaching, coupled with more exposed accessible acidity and enhanced mesoporosity. High dispersion of Pt particles and quantitative metal-acid balance were unable to be the threats for the sequential acid-catalyzed reaction. The cooperative effects of enhanced mesoporosity and highly-accessible acidity accelerated the diffusion and promoted the proximity of metal sites and acid sites, thereby persuading the treated ZSM-48 samples to exhibit excellent activity and iso-selectivity. The i-C16 yield over Pt/ZSM-48(H) catalyst could reach around 86 wt% at conversion rates of 90 wt% with iso-selectivity of 96 wt%. However, the excessively accessible acid sites in Pt/ZSM-48(F) could induce further skeletal transformation and deteriorate the iso-selectivity, although the mesoporous structure was as well established.

为了充分挖掘观光采摘园区内春秋大棚蔬菜的生产潜力,合理利用大棚空间和不同蔬菜对温度、光照的需求差异,昌平区农业技术推广站针对有观光、采摘和餐饮需求的种植园区摸索总结出1种新型栽培模式——苦瓜和叶类蔬菜大棚套种栽培,既合理利用了春秋大棚的生产空间又提高了设施复种指数,而且在生产苦瓜的同时也可以采收2茬以上的叶类蔬菜,观赏和采摘效果俱佳,种植效益增加明显.