Organic transformations using zeolites and zeotype materials

Sulfated Zirconia-Catalyzed Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) Under Solventless Conditions: Competitive Multicomponent Biginelli vs. Hantzsch Reactions

“…The applications of solid acids such as natural and modified clay minerals [2], zeolites and zeotype materials [3] as efficient catalysts in organic transformations have been widely studied. Aside the fact that they have excellent activity and selectivity, even on industrial scales, and in most cases these substances can be recovered from reaction mixtures and reused with good results [4], these solid acids are important from an environmental point of view because they produce less hazardous by-products. In this context, solid sulfated zirconia [5] have been used, due to their acidic and shape-selective nature, for performing the synthesis of heterocycles [6,7], acylation of aromatics ketones [8] and stereocontrolled glycosidations [9], synthesis of aromatic gem-dihalides [10], acylation of crown ethers [11], and chemoselective synthesis of acylals from aromatic aldehydes and their deprotections [12].…”

Remediation of Methyl Tert-Butyl Ether Contaminated Water by Using In situ Catalytic and Biological Combined Techniques

“…Changing the Si/Al ratio can modulate acidity and hydrophobic properties of zeolites [13,19] . Both of the used zeolites showed good catalytic activities toward MTBE hydrolysis reaction, but Z-SUD showed rapid decreasing of initial MTBE concentration as well as a higher rate of MeOH formation.…”

“…Despite of abovementioned reason, it should be noted that the amount of produced TBA in the presence of Z-SYN is lower than Z-SUD, while the amount of produced Alkene is higher, which is in contradiction of what was expected from Si/Al content. Zeolites hydrophobicity can be evaluated as a result of several parameters such as Si/Al ratio in Zeolites frame work, cation present in zeolite structure, synthesis method, structural defects and post-synthesis modification [19,20] . It seems that different catalytic behavior of the investigated catalysts (i.e., type and amounts of the reaction products), can be attributed to the differences in synthesis methods, probable structural defects and post-synthesis treatment of the catalysts.…”

“…Zeolites are three-dimensional, crystalline inorganic compounds, which are built from AlO 4 and SiO 4 tetrahedra. ZSM-5 is a strong solid acid with a characteristic structure containing channels, which allow diffusion of molecules with appropriate size [19][20][21] . Falconer et al [22] were shown that all-silica a zeolite is an effective sorbent for MTBE removal from contaminated waters.…”

Phenol removal from aqueous solutions by using H-mordenite and platinum supported H-mordenite

“…The use of zeolitic materials containing metal active species tetrahedrally coordinated into zeolitic framework for catalytic abatement of phenol. Mordenite is hydrophilic molecules because it has low content of Si/Al ratio close to one [9].…”