Deoxygenation of esters over sulfur-free Ni–W/Al2O3 catalysts for production of biofuel components

Selective Decarboxylation of Fatty Acids Catalyzed by Pd-Supported Hierarchical ZSM-5 Zeolite

“…It is clearly appreciated in Figure 5A that the conversion of stearic acid increases with the aluminum content of the catalyst, varying from a negligible 2% over Pd/h-silicalite to a remarkable 71% over Pd/h-ZSM-5 (33). Taking into account that the three catalysts show a similar Pd content (∼1 wt %), it is concluded that the transformation of the fatty acid also depends heavily upon the acidity of the MFI support.…”

“…Figure 1 illustrates TEM images of the three catalysts, wherein the Pd particles (black dots) may be distinguished over the 100−300 nm size globular particles of the hierarchical MFI supports. The average Pd crystal size was obtained by direct measurements of more than 100 Pd particles in the TEM images, showing that it increased with the Si/Al atomic ratio, from 13 nm [Pd/h-ZSM-5 (33)] to 20 nm (Pd/h-silicalite). This fact provides evidence of the occurrence of interactions between the Pd particles and the Al sites of the zeolitic support that aid to obtain a better metal dispersion.…”

“…As expected, the concentration of both types of acid sites increases with the Al content of the supports. They pointed out a higher ratio of Brønsted/Lewis (C B /C L ) for h-ZSM-5 (33) than for h-ZSM-5 (122) within the range of 150−350 °C and the opposite at 450 °C. Both samples present a relatively high concentration of Lewis acid sites compared to conventional ZSM-5 samples.…”

“…Another important point to unveil is the effect of the MFI support acidity in the activation of the Pd metal sites. To that end, three catalysts having very different acid properties [Pd/hsilicalite, Pd/h-ZSM-5 (122), and Pd/h-ZSM-5 (33)] were tested. It should be notice that Pd/h-silicalite does not contains aluminum in its makeup; therefore, it lacks any mild or strong acidity.…”

“…Crystallization was achieved by hydrothermal treatment at 170 °C for 7 days. The Al-containing materials thus obtained were named as h-ZSM-5 (33) and h-ZSM-5 (122), wherein the number in parentheses represents their actual Si/ Al molar ratio, determined by inductively coupled plasma atomic emission spectroscopy (ICP−AES) analyses. The sample with Si/Al = ∞ was named as h-silicalite-1.…”