Influence of Substrate Concentration on Kinetic Parameters of Ethanol Dehydration in MFI and CHA Zeolites and Relation of These Kinetic Parameters to Acid–Base Properties

Abstract

The catalytic activity of zeolites is often related to their acid–base properties. In this work, the relationship between the value of apparent activation energy of ethanol dehydration, measured in a fixed bed reactor and by means of a temperature-programmed surface reaction (TPSR) depending on the amount of ethanol in the zeolite lattice and the value of activation energy of H/D exchange as a measure of acid–base properties of MFI and CHA zeolites, was studied. Tests in a fixed bed reactor were unable to provide reliable reaction kinetics data due to internal diffusion limitations and rapid catalyst deactivation. Only the TPSR method was able to provide activation energy values comparable to the activation energy values obtained from the H/D exchange rate measurements. In addition, for CHA zeolite, it has been shown that the values of ethanol dehydration activation energies depend on the amount of ethanol in the CHA framework, and this effect can be attributed to the substrate clustering effects supporting the deprotonation of zeolite Brønsted centers.

Investigation of Brønsted acidity in zeolites through adsorbates with diverse proton affinities

“…Zheng et al found a linear correlation between δ 31 P chemical shift of TMPO adsorbed and the proton affinity calculated by DFT 43 , and similar correlations were also found for adsorbed pyridine and acetone 46,47 .The performance of aluminosilicate in a particular reaction or industrial process is of utmost importance (Fig. 1C) [48][49][50][51][52][53][54][55][56][57][58][59][60] . A significant observation is that the concentration of Brønsted acidic sites (BAS) is positively correlated with reaction rates.…”

“…The performance of aluminosilicate in a particular reaction or industrial process is of utmost importance (Fig. 1C) [48][49][50][51][52][53][54][55][56][57][58][59][60] . A significant observation is that the concentration of Brønsted acidic sites (BAS) is positively correlated with reaction rates.…”

Nanocrystalline FeMnO3 Powder as Catalyst for Combustion of Volatile Organic Compounds

“…Table 1 shows the values of the degree of conversion at two temperatures, 290 °C and 500 °C, as well as the values of the kinetic parameters (apparent activation energy and reaction rate) for the oxidation of VOCs studied by the FeMnO 3 catalyst. The values of the apparent activation energies are higher in the case of alcohols and lower in the case of hydrocarbons ( Table 1 ) [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]; also, the catalytic activity starts at much higher temperatures in the case of alcohols compared to hydrocarbons ( Figure 5 ).…”

Template-Free Synthesis of High Dehydration Performance CHA Zeolite Membranes with Increased Si/Al Ratio Using SSZ-13 Seeds

“…The separation factor α, which is expressed by the mole fractions of the components in the feed and the permeate, respectively, is given in Equation ( 1). The permeation flux of each component or the total, J, which is expressed as the permeation amount in weight of each component or the total through the membrane per units of membrane area and time, is given in Equation (2).…”

“…Pervaporation (PV) and vapor permeation (VP) are promising alternative technologies to distillation for the energy-saving separation of azeotropic and near-azeotropic mixtures such as water/ethanol (EtOH) and water/isopropyl alcohol (IPA) [1][2][3][4][5][6]. Zeolite membranes have become the most popular among polymer [7,8], zeolite [9][10][11][12][13], and silica [14,15] membranes because of their excellent separation performance and improved hydrothermal stability.…”