Carbon as a hard template for nano material catalysts

As one of the naturally abundant elements, carbon can present in different molecular structures （allotropes） and thus lead to various physi- cal/chemical properties of carbon-based materials which have found wide applications in a variety of fields including electrochemistry, optical, adsorption and catalysis, etc. On the other hand, its different allotropes also endow carbon-based materials with various morphostructures, which have been recently explored to prepare oxides and zeolites/zeotypes with tailored structures. In this review, we mainly summarize the recent advances in using carbon materials as hard templates to synthesize structural materials. Specifically, we focus on the development in the synthetic strategies, such as endotemplating, exotemplating approaches and using carbon materials as chemical reagents for the synthesis of metal carbides or nitrides, with an emphasis laid on the control of morphostructure. Meanwhile, the applications of the obtained materials will be highlighted, especially, in the field of heterogeneous catalysis where enhanced performances have been achieved with the materials derived from carbon-templated methods.

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600°C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.

Alkaline modification of ZSM-5 catalysts for methanol aromatization： The effect of the alkaline concentration

The effects of alkaline treatment on the physical properties of ZSM-5 catalysts and on their activities for methanol to aromatics conversion have been investigated. A mild alkaline treatment （0.2 and 0.3 mol/L NaOH） created mesopores in the parent zeolite with no obvious effect on acidity. The presence of mesopores gives the catalyst a longer lifetime and higher selectivity for aromatics. Treatment with 0.4 mol/L NaOH decreased the number of Bronsted acid sites due to dealumination and desilication, which resulted in a lower deactivation rate. In addition, more mesopores were produced than with the mild alkaline treatment. As a result, the lifetime of the sample treated with 0.4 mol/L NaOH was almost five times that of the parent ZSM-5. Treatment with a higher alkaline concentration （0.5 mol/L） greatly reduced the number of Bronsted acid sites and the number ofmicropores resulting in incomplete methanol conversion. When the alkalinetreated catalysts were washed with acid, some of the porosity was restored and a slight increase in selectivity for aromatics was obtained.

Self-Assembled Materials for Catalysis

The purpose of this review is to highlight developments in self-assembled nanostructured materials(i.e.,mesoporous and nanoparticle-based materials)and their catalytic applications.Since there are many available reviews of metal-based nanoparticles as catalysts,this review will mainly focus on self-assembled oxide-based catalytic materials.The content includes:(1)design and synthetic strategies for self-assembled mesoporous catalysts,(2)polyoxometalate(POM)-based nanocatalysts,(3)dendrimer-based nanocatalysts,and(4)shaped nanomaterials and catalytic applications.We show that controlled assembly of molecules,crystalline seeds,and nano building blocks into organized mesoscopic structures or controlled morphologies is an effective approach for tailoring porosities of heterogeneous catalysts and controlling their catalytic activities.