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<p>In this research, a non-edible second-generation raw material, <i>Ricinus communis</i> oil, was used as a source of triglycerides for biodiesel production. The reaction was catalyzed with zinc aluminum hydrotalcite, doped with calcium, varying the Ca/Al molar ratio (X = 0.01, 0.03, and 0.05), and with a fixed Zn/Al molar ratio of 2. The ZAC(X) materials were synthesized by coprecipitation and characterized by different physicochemical techniques. The thermal activation at 200&#xa0;°C generates the dehydration and dehydroxylation processes that lead to the formation of Lewis acid-basic pairs (M–O-) and Brönsted basic sites (-OH), along with the formation of a high amount of grafted metal oxides with carbonate anions and hydrozincite, a well-known active crystalline phase. XPS results showed that the calcium-doped catalysts had a relative percentage of hydrozincite of about 48% compared to 31.5% for the undoped catalyst (ZAC(0.0)). Furthermore, the ZAC(0.03) catalyst had the highest M–O-/M-OH site ratio of 1.5. The latter combination generates that ZAC(0.03) shows the best catalytic performance (96.04% FAME yield), which is very close to the EN 14214 standard, maintaining this performance in biodiesel production during 4 reaction cycles without subsequent thermal treatment. The optimal conditions to perform the transesterification reaction of castor oil are 3% w/w of catalyst ZAC(0.03), a molar ratio oil:MeOH 1:30, 200&#xa0;°C as reaction temperature, and 2&#xa0;h as reaction time. The value of the kinetic constant of the ZAC(0.03) was 1.8 × 10<sup>−3</sup> L/gcat.min, which is 2.3 times higher than ZAC(0.0) (k = 0.788 × 10<sup>−3</sup> L/gcat.min) and between 1.45 and 1.70 times higher than the concerning catalysts with Zr and Ce (reported in previous works). Due to the high viscosity (14.358 mm<sup>2</sup>/s) and low cetane number (30.7) of the biodiesel produced from <i>Ricinus communis</i> oil, its use in a blend with diesel is suggested. According to the cost analysis, the price to synthesize the catalysts used in this work was around 0.91 $/g.</p> Graphical Abstract <p></p>

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Assessment of Biodiesel Production from Ricinus Communis Oil over Based Zinc and Aluminum Hydrotalcites Modified with Calcium

  • 期刊论文

  • 发表日期：

    2025年5月23日

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  • Denis A. Cabrera-Munguia,
  • Dora A. Solís-Casados,
  • Adolfo Romero-Galarza,
  • Aída Gutiérrez-Alejandre,
  • Leopoldo J. Ríos-González,
  • Raquel A. López-Montes

摘要

In this research, a non-edible second-generation raw material, Ricinus communis oil, was used as a source of triglycerides for biodiesel production. The reaction was catalyzed with zinc aluminum hydrotalcite, doped with calcium, varying the Ca/Al molar ratio (X = 0.01, 0.03, and 0.05), and with a fixed Zn/Al molar ratio of 2. The ZAC(X) materials were synthesized by coprecipitation and characterized by different physicochemical techniques. The thermal activation at 200 °C generates the dehydration and dehydroxylation processes that lead to the formation of Lewis acid-basic pairs (M–O-) and Brönsted basic sites (-OH), along with the formation of a high amount of grafted metal oxides with carbonate anions and hydrozincite, a well-known active crystalline phase. XPS results showed that the calcium-doped catalysts had a relative percentage of hydrozincite of about 48% compared to 31.5% for the undoped catalyst (ZAC(0.0)). Furthermore, the ZAC(0.03) catalyst had the highest M–O-/M-OH site ratio of 1.5. The latter combination generates that ZAC(0.03) shows the best catalytic performance (96.04% FAME yield), which is very close to the EN 14214 standard, maintaining this performance in biodiesel production during 4 reaction cycles without subsequent thermal treatment. The optimal conditions to perform the transesterification reaction of castor oil are 3% w/w of catalyst ZAC(0.03), a molar ratio oil:MeOH 1:30, 200 °C as reaction temperature, and 2 h as reaction time. The value of the kinetic constant of the ZAC(0.03) was 1.8 × 10−3 L/gcat.min, which is 2.3 times higher than ZAC(0.0) (k = 0.788 × 10−3 L/gcat.min) and between 1.45 and 1.70 times higher than the concerning catalysts with Zr and Ce (reported in previous works). Due to the high viscosity (14.358 mm2/s) and low cetane number (30.7) of the biodiesel produced from Ricinus communis oil, its use in a blend with diesel is suggested. According to the cost analysis, the price to synthesize the catalysts used in this work was around 0.91 $/g.

Graphical Abstract