## 8 Conclusions and Outlook  
In summary, we have presented an overview of the recent development of some composite catalysts based on porous materials for various reactions and processes of interest to the chemical industry. It can be seen that composite catalysts are helpful for achieving high performances. The main conclusions and functions of these composite catalysts are summarized as follows:  
* Regarding amorphous oxide modified zeolite composite catalysts, we have studied amorphous silica decorated zeolite composite catalysts, phosphorus oxide modified zeolite composite catalysts and metal oxide modified zeolite composite catalysts, among which the former are used for selective toluene disproportionation, and the latter two are used for C\({}_{4}\)-olefin cracking to produce propylene. The amorphous silica deposition by SiO\({}_{2}\)-CLD method is to eliminate the external acidic sites of zeolite and reduce the entrance size of zeolite, which are crucial to the high selectivity of _para_-xylene. Because the phosphorus oxide species stabilized by nonframework Al result in a new kind of acid site that is hydrothermally stable, it is a good method for enhancing the anti-coking ability and hydrothermal stability of zeolite composite catalysts. In addition, synergistic catalytic effects have been found by introducing tungsten into phosphorus-modified HZSM-5. * Composite zeolites, such as MWW/FER, BEA/MOR and MOR/MFI were synthesized by co-crystallization or overgrowth. It is found that these composite zeolites are somewhat different from mechanical mixtures of the individual zeolites. Characterizations demonstrate that the composite zeolites may be stacked much closer than in the mechanical mixtures, and intergrowth areas may be formed. Compared with mechanical mixtures of zeolites, composite zeolites have higher acid strength and higher activity for acid reactions (aromaticization of olefins and methanol dehydration), which may be due to their unique composite structures. * As far as hierarchical porous catalysts are concerned, we have tried combine micropores, mesopores and macropores in one catalytic material. Hierarchical porous zeolites, such as silicalite-1, ZSM-5, ZSM-11, Beta were synthesized by using nanosized CaCO\({}_{3}\), starch and polyvinyl butyl gel as templates for the generation of mesopores and macropores. It was found that these hierarchical pores were connective with each other which could facilitate the diffusion of molecules. When studying the process of C\({}_{9}\) aromatics cracking, more C\({}_{10}\) bulky molecules were favorably generated on hierarchical porous zeolites than inside conventional zeolites. Besides, the hierarchical porous zeolites show much lower deactivation rate than conventional zeolites, which could be attributed to the easy transport of molecules with large dimensions through mesopores and macropores. * As for host-guest porous composites, chiral metal complex catalysts can be trapped in the cage of mesoporous materials like SBA-16 by modifying the entrance pore size of the cage using silylation. The entrapped chiral catalyst can be easily recycled without significant loss of catalytic performance and shows catalytic performance comparable to that in a homogeneous catalysis process. The increase in the activity and enantioselectivity with an increase in the number of [Co(salen)] complexes per cage obviously indicates that the cooperative activation effect of [Co(salen)] complexes in the nanocages can be strengthened owing to the crowded situation of the cobalt complexes in the nanocages. In the field of inorganic and organic mesoporous composite catalysts, we have studied mesoporous organosilica composites with sulfonic acid functionalities.