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Modified Vegetable Oils for Environmentally Friendly Lubricant Applications
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Brajendra K. Sharma, Gobinda Karmakar, Sevim Z. Erhan
Several zeolites, such as ZSM-5, Beta Zeolite, and Ferrierite, were recently evaluated for the isomerization of oleic acid [140]. However, among the zeolites, Ferrierite is an excellent candidate for isomerization [141]. Recently, Ngo et al. investigated the isomerization of unsaturated fatty acids to branched FAs using the protonated form of a Ferrierite zeolite [136]. This reaction produced a high yield (>70%) of the isomer where the methyl group is in various positions on the alkyl chain, along with the other by-products. In this isomerization reaction, the degree of conversion of oleic acid was more than 95%. Stearic acid (C18:0) isomerization was evaluated over NiMo/γ-Al2O3-β-zeolites catalysts [142]. In Scheme 24.9, the isomerization of oleic acid using a catalyst is shown. The US patent No. 9, 115,076 B2 disclosed methods of manufacturing branched-chain fatty acids/esters using a combination of a sterically hindered Lewis base and zeolite as a Bronsted or Lewis acid catalyst [143]. Isomerization of oleic acid followed by hydrogenation and methylation.
Isostearic Acids
Published in Brajendra K. Sharma, Girma Biresaw, Environmentally Friendly and Biobased Lubricants, 2016
Helen Ngo, Robert O. Dunn, Winnie C. Yee
A breakthrough in the isomerization process to significantly boost isostearic acid yields using a modified zeolite ferrierite–Lewis base combination method was reported in 2012 and 2014 [41,42]. A zeolite–base isomerization method was developed that maximizes isostearic acid production and minimizes the bimolecular reactions that produce oligomeric (Scheme 4.3, 6) and other by-products (stearic acid [Scheme 4.3, 3], branched- and linear-chain lactones [Scheme 4.3, 4 and 5]) [41,42]. This process involves application of a combination of protonated ferrierite zeolite (H+-ferrierite) catalyst and Lewis base (i.e., triphenylphosphine). Ferrierite is commercially available and was previously used in the skeletal isomerization of butene to isobutene [44–46]. It is found to be an excellent catalyst for isomerization because its acidified form possesses strong acidic sites, providing high activity in the skeletal isomerization of fatty acids. Its interconnected open channels help facilitate the transport of the lipid reactants and products. Triphenylphosphine is used to deactivate (i.e., poison) the active acidic sites on the external surfaces of zeolite particles to suppress dimer acid formation, thereby limiting the bimolecular reactions to the interstitial acidic sites of the zeolite catalyst channels.
Catalytic Applications of Zeolites in Industrial Processes
Published in Subhash Bhatia, Zeolite Catalysis: Principles and Applications, 2020
Other zeolite catalysts such as Pt or Pd/mordenite and ferrierite have also been shown to be effective for lube dewaxing. A lube hydrocracking process, which includes a catalytic dewaxing step, has recently been commercialized by Chevron Inc. for producing high viscosity index lubes.20 Lube yields from the MLDW process are either comparable to or better than that of solvent dewaxing. Table 14 presents some typical yield comparisons based on crude. The by-product yeild is similar to that of the distillate dewaxing process, i.e., one third LPG and two thirds naphtha.
Methods and synthesis parameters affecting the formation of FAU type zeolite membrane and its separation performance: a review
Published in Journal of Asian Ceramic Societies, 2020
Liyana Salwa Mohd Nazir, Yin Fong Yeong, Thiam Leng Chew
Other than that, zeolites may be found in nature as mineral which normally presence in basaltic and volcanic rocks of diverse age, lithology, and geologic setting and are extensively mined all over the world [29]. There are also synthetic zeolites which are commercially made for specific uses. As of 2017, there are 245 unique zeolite frameworks that have been identified and over 40 are naturally occurring zeolite frameworks [30]. In general, zeolite can be classified into 4 categories, according to the dimensions of the pore apertures [31]: Small pore zeolite with apertures consisting of six, eight, or nine tetrahedral (6-, 8, and 9-membered rings) with pore’s diameter of around 4 Å. The most common zeolite in this group are zeolite A (LTA) and chabasite (CHA).Medium pore zeolite frameworks consist of 10 membered rings with pore diameters of 5–6 Å. Example zeolites that belong to this group are zeolite ZSM-5 (MFI) and ferrierite (FER).Large pore zeolites which consist of 12-membered rings with pore diameters of 7 Å. Faujasite (FAU) type zeolite and beta (BEA) are the examples of large pore zeolites.Extra-large pore zeolites with more than 12 membered rings and pore larger than 7 Å. Example of these types of zeolites are CIT-5 (CFI) and ITQ-33 zeolites.