No abstract

Hydrogen is considered one of the most important forms of energy for the future, as it can be generated from renewable sources and reduce CO2 emissions. In this review, the different thermochemical techniques that are currently used for the production of hydrogen from biomass from plantations or crops, as well as those from industrial or agro-industrial processes, were analyzed, such as gasification, liquefaction, and pyrolysis. In addition, the yields obtained and the reactors, reaction conditions, and catalysts used in each process are presented. Furthermore, a brief comparison between the methods is made to identify the pros and cons of current technologies.

The biomass of crops in rotation, such as that generated by the banana plant, is an interesting source of lignocellulose due to its composition and availability. This research aimed to compare the amount of glucose obtained from different parts of the banana plant (leaves, rachis, and pseudostem) by hydrolysis with sulfuric acid at 100 °C. This reaction was analyzed to determine the amount of water and reagents consumed versus the glucose obtained. The optimal time and acid concentration were studied between 0–30 min and 3–5% v/v, respectively. The best results were obtained with the pseudostem of 13.02 gL−1 of glucose in a reaction time of 20 min and an acid concentration of 5%. In addition, the kinetic study of hydrolysis was carried out. The adjustment to the Saeman model was R2 0.96, which represents a first-order reaction and kinetic constants K1 = 0.5 and K2 = 0.3 min−1. This study has shown that these residues can be used as raw materials to generate value-added products due to their high glucose content.

En las últimas décadas, la aplicación de líquidos iónicos (LI) como pretratamiento de la biomasa (BM) residual previo a la reacción de hidrólisis, ha demostrado ser un sistema eficiente para mejorar los rendimientos hacia la obtención de monosacáridos. Una mayor recuperación de monosacáridos, se traduce en un mayor rendimiento en la producción de biocombustibles pudiendo volver a esta industria rentable. En este contexto, la presente revisión bibliográfica analiza las características fisicoquímicas, métodos de síntesis, condiciones de disolución con aplicación de variables tales como: relación LI: BM, temperatura y tiempo. Además, se realiza un análisis comparativo de los resultados de procesos de hidrólisis ácida tradicional con respecto a los obtenidos con la aplicación de líquidos iónicos, aumentado en la mayoría de los casos sus rendimientos de reacción.  Finalmente, se mencionan algunas técnicas de recuperación y reciclaje, que permitan reducir los costos del proceso, de manera que este sea económicamente rentable.

Hydrogen produced from biomass is an alternative energy source to fossil fuels. In this study, hydrogen production by gasification of the banana plant is proposed. A fixed-bed catalytic reactor was designed considering fluidization conditions and a height/diameter ratio of 3/1. Experimentation was carried out under the following conditions: 368 °C, atmospheric pressure, 11.75 g of residual mass of the banana (pseudo-stem), an average particle diameter of 1.84 mm, and superheated water vapor as a gasifying agent. Gasification reactions were performed using a catalyzed and uncatalyzed medium to compare the effectiveness of each case. The catalyst was Ni/Al2O3, synthesized by coprecipitation. The gas mixture produced from the reaction was continuously condensed to form a two-phase liquid–gas system. The synthesis gas was passed through a silica gel filter and analyzed online by gas chromatography. To conclude, the results of this study show production of 178 mg of synthesis gas for every 1 g of biomass and the selectivity of hydrogen to be 51.8 mol% when a Ni 2.5% w/w catalyst was used. The amount of CO2 was halved, and CO was reduced from 3.87% to 0% in molar percentage. Lastly, a simulation of the distribution of temperatures inside the furnace was developed; the modeled behavior is in agreement with experimental observations.