Solid acid catalysts from clays: Acid leached metakaolin as isopropanol dehydration and 1-butene isomerization catalyst

Preparation and Characterization of Dealuminated Metakaolin and Its Use in the Transformation of Waste Plastics to Aromatic Hydrocarbons

“…Clearly, an appropriate choice of activation parameters (acid strength, temperature, time) can control the degree of structural degradation and hence the characteristics of the activated products. The relative amounts of dealumination agree with the results of Perissonoto et al (31) in that the Si/Al ratio after treatment with 6M HCl are the same at 12.6 ± 0.1.…”

“…Transformation agents were prepared by acid activation of a metakaolin derived from a well-crystallized Cornish kaolin from English China Clays, according to the method of Perissinoto et al (31).…”

“…The high octahedral aluminum content makes kaolin resistant to acid leaching (28,29), but metakaolin (produced by heating kaolin in air at temperatures > 450 • C (29)) is much more susceptible to acid activation, producing a catalyst with the same activity as acid activated montmorillonite at about half the fresh surface area (29). Thus, acid-activated metakaolin (AAMK) is a material which offers both enhanced surface area and acidity compared with either kaolin or metakaolin (29)(30)(31). As with acid treated bentonites, the activity of AAMKs reaches a maximum and then declines as the severity of the activation process increases although Lussier has reported that AAMKs with high surface areas and activities can be prepared using very low acid concentrations if the metakaolin was produced in a narrow calcination window (29).…”

Esterification of Fatty Acids with Short-Chain Alcohols over Commercial Acid Clays in a Semi-Continuous Reactor

“…Acid-activated clays are one of the most widely studied solid acid catalysts for many organic transformations such as alkylation [17,18], condensation [19], dimerisation [20], isomerisation [21], ether formation [22] and transesterification reactions [23], but they are rarely used as catalyst in esterification reactions.…”

Room-temperature isomerization of 1-butene to 2-butene over palladium-loaded silica nanospheres catalyst

“…Perissinotto et al [14] prepared a series of acid-leached metakaolin and tested the catalytic performance of 1-butene doublebond-shift isomerization. The highest conversion was about 90.0% with a selectivity of 71.7%, even under the harsh reaction conditions (T = 400°C).…”