Esterification of levulinic acid with butanol over ion exchange resins

Abstract

Alkyl levulinates are biobased chemicals with a great number of applications and great biofuel potential for blending to conventional diesel or gasoline. The present work focuses on the liquid-phase synthesis of butyl levulinate (BL) by esterification of levulinic acid (LA) with 1-butanol (BuOH) using a set of acidic ion-exchange resins. Experiments were performed at 80ºC and 2.5 MPa in a batch reactor by using an initial molar ratio AL/BuOH of 1/3 and a catalyst loading of 0.8%. It has been found that BL could be successfully obtained over ion-exchange resins with a selectivity higher than 99.5%. LA conversions ranged from 64% (Amberlyst 46, macroreticular, surface sulfonated) to 94% (Dowex 50Wx2, gel-type resin, conventionally sulfonated) at 8 h reaction time. By comparing their catalytic behavior, it was seen that resins morphology plays a very important role in the synthesis of BL making easier the access of reactants to acid sites. Accessibility of LA and BuOH to acid centers was high over highly swollen and low polymer density resins. Thus, gel-type resins with low divinylbenzene (DVB) content have been found as the most suitable to produce BL, e.g. Dowex 50Wx2, Dowex 50Wx4 and Purolite® CT224. Among them, Dowex 50Wx2 (2% DVB) is the most efficient catalyst tested.

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

“…Despite encouraging literature precedents [22,33], Amberlyst 15 gave only 52% conversion of 1 within 2 h (Table 1, entry 5, 31% yield). We then switched to perfluorinated resins.…”

“…Although the behaviour of many metal oxides has been investigated, reports featuring the activity of supported organic Brønsted acids are very few. In particular, Tejero reported that sulfonic acid supported on polymeric resins could catalyse the esterification of LA, providing conversions up to 94% upon warming at 80 °C for 8 hours in the presence of 3 equiv of n -butanol [33]. Melero described the synthesis of mesostructured silica frameworks featuring pending organosulfonic arms.…”

Role of ion‐exchange resins as catalyst in the reaction‐network of transformation of biomass into biofuels

“…A resins screening among several macroreticular and gel‐type resins with different crosslinking degree and sulfonation procedure (Amberlyst‐15, ‐16, ‐35, ‐36, ‐39, ‐46, ‐70, Purolite CT‐224, Dowex 50Wx2, x4, x8) was carried out in order to select suitable catalyst for obtaining BL and to find a possible effect of resins morphology on the catalytic activity. At 353 K and 2.5 MPa with a slight alcohol excess, BL was successfully obtained with selectivity higher than 99.5% for all the resins . By comparing the catalytic behavior, it was seen that resins morphology plays a very important role in BL synthesis.…”

“…A very recent paper of our group was devoted to the study of the synthesis of BL over sulfonated resins. 69 A resins screening among several macroreticular and gel-type resins with different crosslinking degree and sulfonation procedure (Amberlyst-15, -16, -35, -36, -39, -46, -70, Purolite CT-224, Dowex 50Wx2, x4, x8) was carried out in order to select suitable catalyst for obtaining BL and to find a possible effect of resins morphology on the catalytic activity. At 353 K and 2.5 MPa with a slight alcohol excess, BL was successfully obtained with selectivity higher than 99.5% for all the resins.…”

Efficient Production of N-Butyl Levulinate Fuel Additive from Levulinic Acid Using Amorphous Carbon Enriched with Oxygenated Groups

“…However, the literature on the synthesis of BL via the esterification of LA are sparse. Several types of solid acids such as supported montmorillonite [21], zeolites [22,23], metal-organic frameworks [24], Al-MCM-41 [25], ion-exchange resins [26,27], graphene oxide [28] and immobilized lipase [29] have been utilized in the esterification of LA with n-butanol. Surprisingly, the catalysis with amorphous carbon materials to produce BL has not been explored before.…”