Eliana Ramírez

Esterification of levulinic acid with butanol over ion exchange resins

Amberlyst 15 111 ± 2 110 ± 3 4.70 ± 0.1 4.73 ± 0.1 4.81 48 80 Amberlyst 35 117 ± 2 5.20 ± 0.1 5.32 48 Amberlyst 16 108 ± 3 4.72 4.80 80 Amberlyst 36 117 ± 2 5.30 ± 0.1 5.40 48 Amberlyst 39 111 ± 3 4.66 4.82 80 Amberlyst 70 117 ± 3 1.65 ± 0.05 2.55 48 Dowex 50Wx4 113 ± 3 4.65 4,95 80 Dowex 50Wx2 106 ± 3 3.80 4.83 80 Purolite CT224 112 ± 3 4.51 5.34 80 Amberlyst 46 108 ± 3 0.91 0.87 80 The experimental technique can be found in Siril et al. [48] a From microcalorimetry of NH3 adsorption. It considers those centers with -HNH3 ≥ 80 kJ/mol b From titration with NaOH

Green metrics analysis applied to the simultaneous liquid-phase etherification of isobutene and isoamylenes with ethanol over Amberlyst™ 35

Abstract A case study of the green metrics analysis of several processes is described. The considered system is the simultaneous etherification of isobutene and isoamylenes with ethanol over Amberlyst™ 35. Experimental results are compared under the green metrics methodology with those for the isolated ethyl tert-butyl ether and tert-amyl ethyl ether syntheses previously reported over acid ion-exchange resins using different reaction batch devices and different synthesis pathways, such as the production of both ethers from tertiary alcohols and from ethanol. The best results, from an environmental point of view, were obtained for ether syntheses from olefins and ethanol in terms of the parameters measured in the green metrics analysis. A process allowing the separation of ethers from the product stream and the reactants recirculation has been proposed and simulated. The suggested process depicts a suitable alternative for the simultaneous production of tertiary ethers from pure olefin feed and their downstream implementation as greener fuel additives with environmental benefits.

Synthesis of ethyl hexyl ether over acidic ion-exchange resins for cleaner diesel fuel

The synthesis of ethyl hexyl ether as a suitable diesel additive was investigated using 1-hexanol and diethyl carbonate as reactants and acidic ion-exchange resins as catalysts. Liquid-phase experiments were performed in a batch reactor at the temperature range of 403–463 K and 2.5 MPa. The formation of ethyl hexyl ether proceeded from two routes: thermal decomposition of ethyl hexyl carbonate and intermolecular dehydration of 1-hexanol with ethanol. Both pathways require a previous transesterification reaction between diethyl carbonate and 1-hexanol. It was revealed that this reaction is favoured in polymer zones of 0.4 nm nm−3 polymer density (equivalent to 2.6 nm diameter pores in inorganic materials). Acidic ion-exchange resins containing a significant volume fraction of this polymer density are Dowex 50W×2 and Amberlyst 70. By using this kind of catalyst, reaction rate and selectivity are significantly increased. Finally, it was observed that working at low temperature would favour the selectivity to ethyl hexyl carbonate and hinder the undesired formation of alkenes.

Simultaneous etherification of isobutene with ethanol and 1-butanol over ion-exchange resins

The simultaneous liquid-phase etherification of isobutene with ethanol and 1-butanol to give ethyl tert-butyl ether (ETBE) and butyl tert-butyl ether (BTBE) has been studied, at temperatures in the range of 315–353 K and at 2.5 MPa, over six commercial acidic macroreticular ion-exchange resins as catalysts. The initial alcohol to isobutene molar ratio was varied in the range of 0.5–5.5 and the initial ethanol to 1-butanol molar ratio in the range of 0.5– 2.0. Strongly acidic catalysts with a rigid polymer backbone structure enhance reaction rate. This fact, along with the reduced side reactions extent, makes AmberlystTM 35 the most promising catalyst, among the tested ones, for the studied simultaneous etherification process. Irrespectively of the used catalyst, initial ETBE synthesis reaction rate is hardly sensitive to the variation of the ethanol to 1-butanol molar ratio, whereas initial BTBE synthesis reaction rate strongly diminishes at high ethanol concentration. Preferential adsorption of ethanol over 1-butanol on the catalysts active sites has been detected. As expected, both etherification reaction rates increase at increasing isobutene concentration. At 353 K, the highest temperature, both etherification rates are affected by internal mass transfer resistances due to diffusion limitations even when small catalyst beads are used. The simultaneous process has been compared to the individual syntheses of ETBE and BTBE and it has been found that the isobutene selectivity towards ethers is enhanced in the simultaneous system.

Catalytic activity dependence on morphological properties of acidic ion-exchange resins for the simultaneous ETBE and TAEE liquid-phase synthesis

The simultaneous liquid-phase synthesis of 2-ethoxy-2-methylpropane (ETBE) and 2-ethoxy-2-methylbutane (TAEE) has been studied over fifteen commercial acidic ion-exchange resins. Kinetic experiments were carried out in a batch reactor at T = 335 K and initial molar ratios of alcohol to olefins (R°A/O) and between olefins (R°C4/C5) of 1.1 and 1, respectively. The catalytic activity, measured as intrinsic initial etherification rates, has been found to decrease in the order: Amberlyst™ 35 > Amberlyst™ 48 > Purolite® CT-275 > Amberlyst™ 15 > Purolite® CT-175 > Amberlyst™ 40 > Amberlyst™ 36 > Amberlyst™ 16 > Purolite® CT-482 > Amberlyst™ 39 > Amberlyst™ DT > Amberlyst™ 45 > Purolite® CT-124 > Purolite® MN-500 > Amberlyst™ 46. This catalytic activity rank is related to the morphological properties of the resins in both dry and swollen states. The ratio of acid capacity to specific volume of the swollen polymer has been found to be the main catalyst properties that determine their activity: the higher the ratio, the higher the activity.