Diffusion and catalyst efficiency in hierarchical zeolite catalysts

The preparation of hierarchical zeolites with reduced diffusion limitation and enhanced catalyst efficiency has become a vital focus in the field of zeolites and porous materials chemistry within the past decades. This review will focus on the diffusion and catalyst efficiency of hierarchical zeolites and industrial catalysts. The benefits of diffusion and catalyst efficiency at two levels of hierarchies (zeolitic component level and industrial catalyst level) from a chemical reaction engineering point of view will be analysed. At zeolitic component level, three types of mesopores based on the strategies applied toward enhancing the catalyst effectiveness factor are presented: (i) 'functional mesopores' (raising effective diffusivity); (ii) 'auxiliary mesopores' (decreasing diffusion length); and (iii) 'integrated mesopores' (a combination thereof). At industrial catalyst level, location and interconnectivity among the constitutive components are revealed. The hierarchical pore interconnectivity in multi-component zeolite based industrial catalysts is exemplified by fluid catalytic cracking and bi-functional hydroisomerization catalysts. The rational design of industrial zeolite catalysts at both hierarchical zeolitic component and catalyst body levels can be fully comprehended using the advanced in situ and/or operando spectroscopic, microscopic and diffraction techniques.

Preparation of hierarchical catalysts with the simultaneous generation of microporous zeolite using a template and large mesoporous silica by gel skeletal reinforcement and their reactivity in the catalytic cracking of n-dodecane

Zeolite-containing hierarchical mesoporous catalysts prepared using gel skeletal reinforcement exhibited the superior activity and selectivity in n-dodecane catalytic cracking.

A hierarchical zeolitic Murray material with a mass transfer advantage promotes catalytic efficiency improvement

A rationally designed hierarchical zeolitic Murray material exhibited highly enhanced mass transfer and terrific catalytic activity.

Hydrocracking of Jatropha Oil over non-sulfided PTA-NiMo/ZSM-5 Catalyst

The PTA-NiMo/ZSM-5 catalyst impregnated with phosphotungstic acid (PTA) was designed for the transformation of Jatropha oil into benzene, toluene, and xylenes (BTX) aromatics. The produced catalyst was characterized by N₂ adsorption-desorption, powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and the temperature-programmed desorption of ammonia (NH₃-TPD). The catalytic performance was evaluated by gas chromatography (GC). The liquid products were 70 wt% of the feed oil, and the majority of the liquid products were BTX. The aromatization activity of the catalyst was improved by the addition of PTA and the hierarchical process. The favorable PTA amount was 20 wt% and the yield of BTX was 59 wt% at 380 °C, 3 MPa, H₂/oil (v/v) = 1000 and LHSV = 1 h⁻¹ over the PTA20-NiMo/HZ0.5 catalyst (PTA 20 wt%) without sulfurization.

A mesoporous aluminosilicate prepared by simply coating fibrous γ-AlOOH on the external surface of SBA-15 for catalytic hydrocarbon cracking

Coating fibrous γ-alumina stabilized the SBA-15 structure against collapse in steam, allowing for the facile synthesis of mesoporous aluminosilicate which showed excellent catalytic performance in the cracking of 1,3,5-triisopropyl benzene.

Applied catalysis for sustainable development of chemical industry in China

Progressing green chemical technologies is significant to the sustainable development of chemical industry in China, as the energy and environment problems increasingly became great challenges to the whole society. The scientific connotation of sustainable energy chemical engineering can be generalized as green carbon/hydrogen science which means optimization of carbon/hydrogen atom economics based on high efficient catalysis and low-carbon emission. This review illustrated recent advances in developing sustainable technologies for applied catalysis in chemical industry of China, including the fields of high efficient conversion of heavy oil, green petrochemical catalytic technologies, clean utilization of coal and natural gas, promoting sustainable resources and clean energy, etc. Moreover, from the view of industrial point, some important common scientific problems were discussed and summarized, such as the relation between molecular diffusion and catalyzing efficiency, homogeneous catalysis in heterogeneous catalysts, in situ or operando characterization of industrial catalysis, etc., aiming to supplying a forward roadmap to academia and/or industry.