Propylene is a very essential building block in the petrochemical industry. There is a fast growing in its demand that is steadily expanding its market. Fluid catalytic cracking units is the second largest propylene source for petrochemical application. FCC units are primarily used in the production of gasoline. However, refiners have taken advantage with the aim of producing and recovering large amounts of propylene from their Fluid catalytic cracking unit by raising the severity of reaction through riser temperature, installation of a propylene recovery unit and addition of a catalyst that is shape selectivity.

ZSM-5 is nowadays used as a very efficient fluid catalytic cracking additive for increasing light olefins production i.e. propylene. This short review will be exclusively focused on ZSM-5-containing additives and look at the main strategies used in the design and modifications of ZSM-5 catalysts to increase the propylene production in the FCC units. The review will highlight the most important and the recent modification methods used in enhancing ZSM-5 performance in the FCC process to maximize the yield of light olefins in general, and in particular that of propylene.

These methods include particle size and acidity modification, phosphorus treatment, mesoporous/hierarchical structure creation, incorporation alkali metals and some selected transition metals and introduction of rare-earth metal.

FEIZHOU Attapulgite is added into painting and coatings for rheological control.It can effectively prevent sedimentation and delamination of pigments, improve the weatherability and scratch resistance of coatings, and improve the bonding strength between coatings and substrates.

1. In wall coatings, FEIZHOU Attapulgite helps to prevent the paint from flowing down and to improve the smoothness of the wall surface. What’s more,it can greatly improve the scratch resistance and aging time of the exterior wall coating, and also the bonding strength between the coating film and the wall, the hardness of the coating film and the surface self-cleaning ability

2. When FEIZHOU Attapulgite is adsorbed by powder coatings, movable layer is formed on its surface.It improves flowing property by preventing powder coatings from absorbing moisture and agglomerating.

3. The main function of FEIZHOU Attapulgitein floor paint is to improve its ability of weather resistance, scratch resistance and leveling performance.

The thickening and thixotropy property of FEIZHOU Attapulgite is mainly related to its unique structure. FEIZHOU Attapulgite is light grey powder.

But in microscopic state, FEIZHOU Attapulgite is electrically charged rod-shaped particles -like mesh structure. The cross needle structure forms mesh structure thus results in good thickening performance.

The force of mesh structure and the physical adsorption force are relatively weak, when shear thinning is applied, this network is easy to break,viscosity decreases; when shear thinning is removed, network is restored,viscosity increases, thixotropic property shows.

When thickening and thixotropic agent is added into your product, thickening and thixotropy property is gained FEIZHOU Attapulgite is one of the most common used agents for this purpose. Except from the good behavior in thickening and thixotropy property, FEIZHOU Attapulgite  has other special properties.  That’s the reason why FEIZHOU Attapulgite is the preferred choice for a lot of applications, including coatings application.

Thickening means the increase in viscosity;Thixotropy is closely related with shear thinning. Shear thinning means that the viscosity of a liquid changes in relation to shear stress - it is dependent on the force acting on the coating film. At high levels of shear stress, lower viscosity is observed. This viscosity increases when the shear stress is reduced. The effect of a liquid increasing in viscosity as the duration of shear exposure increase, while the shear intensity remains constant, is referred to as thixotropy.

Zeolite molecular sieve is a aluminosiliate with uniform pores. These pore diameters are similar in size to small molecules. Thus molecules with diameter less than the pore size can enter molecular sieve and be adsorbed, while molecules with diameter bigger than the pore size can not go into molecular sieve and be excluded (Tab. 1). Moreover, molecular sieve pore size can be precisely adjusted through introducing of different metal ions such as Na+(4A, 13X), K+(3A), Ca+(5A, CaX), Li+(LiLSX, LiLX). This property enables molecular sieve to separate molecules of different size. Another important property of molecular sieve is it is easier to adsorb polar molecules other than non polar molecules, thus makes it possible to separate molecules by its polarity (Fig. 1).

Tab.1 pore size of different kinds of molecules

Molecular Sieve Application