Progress in Seed-assisted Synthesis of (Silico)Aluminophosphate Molecular Sieves

Advanced solid-state NMR spectroscopy and its applications in zeolite chemistry

Solid-state NMR spectroscopy (ssNMR) can provide details about the structure, host-guest/guest-guest interactions and dynamic behavior of materials at atomic length scales. A crucial use of ssNMR is for the characterization of zeolite catalysts that are extensively employed in industrial catalytic processes. This review aims to spotlight the recent advancements in ssNMR spectroscopy and its application to zeolite chemistry. We first review the current ssNMR methods and techniques that are relevant to characterize zeolite catalysts, including advanced multinuclear and multidimensional experiments, in situ NMR techniques and hyperpolarization methods. Of these, the methodology development on half-integer quadrupolar nuclei is emphasized, which represent about two-thirds of stable NMR-active nuclei and are widely present in catalytic materials. Subsequently, we introduce the recent progress in understanding zeolite chemistry with the aid of these ssNMR methods and techniques, with a specific focus on the investigation of zeolite framework structures, zeolite crystallization mechanisms, surface active/acidic sites, host-guest/guest-guest interactions, and catalytic reaction mechanisms.

Advancements in Basic Zeolites for Biodiesel Production via Transesterification

The excessive utilization of petroleum diesel has led to the depletion of fossil resources and severe environmental pollution. Biodiesel produced from renewable triglycerides (TGs) or waste lipids is a low-emission fuel substitute for diesel. Biodiesel is mainly produced by transesterification reactions over homogeneous base catalysts with excellent activity and low cost. In comparison, solid base catalysts are more attractive due to their lower environmental impact and simpler production and purification processes. It remains a challenge to further improve the stability and activity of solid base catalysts. Because of the high surface area, superior stability, and tunable basicity, basic zeolites, especially two-dimensional zeolites, have emerged as promising solid basic catalysts for the transesterification of TGs. In this review, we present recent advancements in the synthesis, characterization, and catalytic performance of basic zeolites for the transesterification of TGs. Challenges and development prospects of basic zeolites for biodiesel production via transesterification are also pointed out. We expect that this review will inspire the more efficient and rational design of zeolites for sustainable fuel production.

Small pore SAPO-14-based zeolites with improved propylene selectivity in methanol to olefins

Methanol to olefins (MTO) is an important non petroleum route to prepare light olefins, however, it still remains a challenge to improve the one-pass propylene selectivity towards the industrial SAPO-34...