An intracrystalline catalytic esterification reaction between ethylene glycol intercalated layered double hydroxide and cyclohexanecarboxylic acid

Microwave-Assisted Synthesis of Ethylene Glycol-Intercalated NiAl LDHs and Their Application for Intracrystalline Catalytic Esterification with Naphthenic Acids in Crude Oil

“…Third, 0.84 g of KOH was added into the system followed by stirring and irradiating at 100 °C for 15 min. The addition of KOH is to capture the proton from EG, which could facilitate the exchange of NO 3 – by EG, as reported previously. , The amount of KOH is chosen by a series of experiments with various KOH amounts at which more ordered EG-intercalated LDHs can be obtained. Finally, the product was collected by filtrating, washing with acetone several times to remove the excess EG, and drying at 80 °C for 6 h in vacuum.…”

“…Due to the versatility of layer metal cations and interlayer anions, the properties of LDHs are highly tunable . LDHs can be used as catalysts for esterification between acids and alcohols, − and recently, they were applied as esterification catalysts to remove naphthenic acids from oil. , Ethylene glycol (EG) is the most commonly used alcohol for esterification with naphthenic acids in oil ,− due to its low cost and high boiling point. However, there remains much room for improvement of the catalytic efficiency of LDHs during the esterification with EG, because the highly viscous EG may lead to serious diffusion resistance.…”

“…Compared with the methods reported in the literature, the ion exchange time was greatly shortened from several days to 12 h by the assistance of KOH. On the basis of the EG-intercalated NiAl LDHs, the intracrystalline catalytic esterification between EG and cyclohexanecarboxylic acid was achieved, which exhibited a much higher acid removal ratio and EG conversion than the conventional bulk catalytic reaction over nitrate NiAl LDHs . However, only EG-intercalated LDHs with a Ni/Al ratio of 2 was synthesized and used as the intracrystalline esterification catalyst.…”

Esterification of naphthenic acids with various structures over tungstophosphoric acid-intercalated layer double hydroxide catalysts with various interlayer spacings

“…Reactants must be close to the edges of LDHs or enter the interlayer to adsorb and react with the active sites (Hu et al, 1998;Guo et al, 2001). Such a reaction can be considered as an interlayer catalytic reaction in which the interlayer of LDHs provides both the catalytic sites and the reaction field (Wang et al, 2015;She et al, 2021). Some researchers also immobilized the catalytic sites in the interlayer of LDHs and developed various interlayer reactions in a nanosized confined region (An et al, 2006;Shi et al, 2010;Shi & He, 2011;Liu et al, 2013;Chen et al, 2015;Varga et al, 2016;She et al, 2021).…”

Fotokatalizátor és nanoreaktor

“…Léteznek példák rétegközi észterképződési reakcióra, mint például a NiAl-LDH rétegei között lejátszódó (interkalált) etilén-glikol és ciklohexán-karbonsav részvételével történő reakció. A kapott eredmények alapján az észterképződés nemcsak, hogy sikeres volt, hanem az LDH alkalmazása mellett az észterre vonatkozó konverzió 91%-ra nőtt az oldat fázisban tapasztalt 7,22%-os konverzióhoz képest [125]. Egy másik típusú észterezési reakcióban ZnCr-, ZnAl-, MgAl-, CuCr-és CoAl-LDH rétegei közé interkalált benzoát-, illetve acetát ionoknak o-alkilezési reakcióit vizsgálták benzilbromiddal illetve 1-bromooktánnal ultrahangos besugárzás mellett, oldószermentes körülmények között.…”