The present invention relates to a process for preparing zeolite crystals having a multimodal particle size distribution, and the sizes of which are between 0.02 μm and 20 μm, said process comprising a first introduction of one or more seeding agents into the tubular reactor or upstream of the tubular reactor, and at least one second introduction of one or more, identical or different, seeding agents into the tubular reactor.

The present invention relates to a process for preparing zeolite crystals having a multimodal particle size distribution, and the sizes of which are between 0.02 μm and 20 μm, said process comprising a first introduction of one or more seeding agents into the tubular reactor or upstream of the tubular reactor, and at least one second introduction of one or more, identical or different, seeding agents into the tubular reactor.

The present disclosure provides a sound absorbing material. The sound absorbing material comprises MFI-structural-type zeolite. The MFI-structural-type zeolite comprises a framework, and the framework comprises SiO.sub.2 and AlO.sub.3, and the mass ratio of Si to Al in the framework is less than 200 and not less than 50. The present disclosure also provides a speaker box applying the sound absorbing material. The sound absorbing material provided by the present disclosure and the speaker box using the sound absorbing material can further improve the performance of the speaker box, reduce the failure of zeolite and improve the performance stability of the speaker box.

Systems and methods for production of externally-pore-blocked, internally-pore-opened modified zeolite crystals, the method including mixing zeolite crystals with an organic pore blocking agent; heating the zeolite crystals mixed with the organic pore blocking agent to block internal pores of the zeolite crystals and produce internally-pore-blocked zeolite crystals; mixing the internally-pore-blocked zeolite crystals with an external pore blocking agent; and calcining the internally-pore-blocked zeolite crystals mixed with the external pore blocking agent, to re-open internal pores via decomposition of the organic pore blocking agent and to block external pores via formation of a silica layer over external pores of the zeolite crystals, forming the externally-pore-blocked, internally-pore-opened modified zeolite crystals.

Systems and methods for production of externally-pore-blocked, internally-pore-opened modified zeolite crystals, the method including mixing zeolite crystals with an organic pore blocking agent; heating the zeolite crystals mixed with the organic pore blocking agent to block internal pores of the zeolite crystals and produce internally-pore-blocked zeolite crystals; mixing the internally-pore-blocked zeolite crystals with an external pore blocking agent; and calcining the internally-pore-blocked zeolite crystals mixed with the external pore blocking agent, to re-open internal pores via decomposition of the organic pore blocking agent and to block external pores via formation of a silica layer over external pores of the zeolite crystals, forming the externally-pore-blocked, internally-pore-opened modified zeolite crystals.

A process of performing controlled alkaline treatments on inorganic porous solids, yielding superior physico-chemical and catalytic properties, whereby the particle and crystal size is not negatively influenced. The solids obtained from this process can be easily recovered from the alkaline solution.

The present invention relates to a process for preparing zeolite crystals continuously, comprising the continuous introduction of a composition capable of generating zeolite crystals into at least one crystallization reaction zone subjected to stirring means, giving said composition a flow characterized by a relative Reynolds number Re.sub.r of between 40 and 50 000, and the continuous recovery of the crystals formed according to a flow characterized by a net Reynolds number Re.sub.n of between 1 and 1500.

The present invention relates to a process for preparing zeolite crystals continuously, comprising the continuous introduction of a composition capable of generating zeolite crystals into at least one crystallization reaction zone subjected to stirring means, giving said composition a flow characterized by a relative Reynolds number Re.sub.r of between 40 and 50 000, and the continuous recovery of the crystals formed according to a flow characterized by a net Reynolds number Re.sub.n of between 1 and 1500.

Compositions and methods for preparing mesoporous and/or mesostructured materials from low SAR zeolites are provided herewith. In particular, methods are provided that involve: (a) providing a low SAR zeolite, (b) optionally subjecting the low SAR zeolite to an acid framework modification, and (c) subjecting the framework-modified zeolite to a mesopore formation treatment. The resulting mesoporous zeolites can have bi-modal mesoporosity and higher aluminum contents relative to existing mesoporous zeolites.

Compositions and methods for preparing mesoporous and/or mesostructured materials from low SAR zeolites are provided herewith. In particular, methods are provided that involve: (a) providing a low SAR zeolite, (b) optionally subjecting the low SAR zeolite to an acid framework modification, and (c) subjecting the framework-modified zeolite to a mesopore formation treatment. The resulting mesoporous zeolites can have bi-modal mesoporosity and higher aluminum contents relative to existing mesoporous zeolites.