Browsing by Autor "Ronald M. Lara Prado"

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pantalla táctil en el interior de parednthesis of ZSM -5 zeolite using Diatomite as precursor; its application in the Methanol to hydrocarbons process (mth)
(2019) Ronald M. Lara Prado; Dayana M. Capcha Vargas; Yamil Acho Sarzuri; Edgar CÃ¡rdenas; Gustavo GarcÃa; SaÃol Cabrera M; Luis LÃ pez N
Pyrolysis of açai stems (Euterpe oleracea Mart.) and cocoa husks (Theobroma cacao L.) residues for the generation of added-value products in rural areas
(Springer Nature, 2024) Ronald M. Lara Prado; Rodrigo Surculento Villalobos; Luis Felipe López; Henrik Kušar
Abstract Generally, agriculture activities represent the main economic income of rural areas, and during these, huge amounts of biomass are generated. This biomass is considered as garbage due to its high storage cost. However, energy and added-value products can be recovered from biomass. Within this context, açai stems and cocoa husks were collected from different rural areas of Bolivia due to their high importance in the local and international markets as two of the most available products of the country. The preliminary study will contribute in the field of green energy recovery and resource management. Thus, in this study, both residues were tested as renewable feedstocks for the generation of added-value products from pyrolysis at 500 °C for 30 min. Açai stems were found to be more suitable to biochar based with yields up to 49.1% ± 2.4%, but also for biogas production (33.9% ± 2.0%). Cocoa husk was also found to be more suitable for biochar production (38.1% ± 1.7%) but also for bio-oils (33.6% ± 17.6%). Both resulting biochars had basic pH (between 10 and 12) and low density (287.2 kg/m 3 and 401.7 kg/m 3 ). Additionally, the lack of heavy metals on the surface makes both biochar products good candidates for soil amendment applications. Furthermore, the bio-oil composition is complex and varied, and products such as Maltol, 2-methyl furane, and D-allose have direct applications in the food industry. Moreover, the presence of phenolic compounds and hydrocarbons with more than five carbons in the structure makes the obtained bio-oils suitable for upgrading processes for biofuel production. Finally, the obtained biogases can be applied for local electricity generation, or to reduce the energy requirements for the pyrolysis reactor. Graphical Abstract
SÍNTESIS DE ZEOLITA ZSM-5 UTILIZANDO DIATOMITA COMO PRECURSOR; SU APLICACIÓN EN EL PROCESO DE METANOL A HIDROCARBUROS (MTH)
(2019) Ronald M. Lara Prado; Dayana M. Capcha Vargas; Yamil Acho Sarzuri; Edgar Cárdenas; Gustavo García; Saúl Cabrera M.; Luis Lopez N; Saúl Cabrera M.; Luis López N.
Zeolite H-ZSM-5 is widely applied in the petrochemical industry, such as the synthetic process of methanol to hydrocarbons (methanol to hydrocarbons MTH). ZSM-5 zeolite is currently obtained through reagents and expensive processes, being available only a few cheaper alternative routes. In the present investigation, zeolite H-ZSM-5 was obtained from natural diatomite, then characterized, and finally tested in the synthetic MTH process. The natural diatomite was treated with sulfuric acid to perform hydrothermal synthesis with tetrapropyl ammonium hydroxide (TPA-OH). As a result, the H-ZSM-5 zeolite obtained had a Si / Al molar ratio of 23, it exhibited high thermal stability and showed Lowry-Brnsted and Lewis acid sites. The application of this zeolite in the MTH reaction showed a methanol conversion of 88%. The products were: dimethyl ether (DME) in 40%, olefins (mostly ethylene and propylene) in 40% and others in 20%. The reaction conditions were: 300 C, 1.2L metanol /g cat h at atmospheric pressure (0.65 bar). The selectivity of the products can be modified in such a way that DME can be
SÍNTESIS DIRECTA DE ETER DIMETÍLICO DE SYNGAS. PARTE I: PREPARACIÓN DE LOS CATALIZADORES BIFUNCIONALES DE CuO-ZnO / HZSM-5 POR SÍNTESIS SUCESIVA Y MEZCLA FÍSICA.
(2019) Dayana M. Capcha Vargas; Ronald M. Lara Prado; Yamil Acho Sarzuri; Saúl Cabrera; Luís A. López
La síntesis directa de dimetiléter a partir de gas de síntesis (CO + H2) requiere de catalizadores bifuncionales tipo CuO-ZnO/HZSM-5, donde el CuO-ZnO realiza la síntesis de metanol dada su función de hidrogenación y la zeolita HZSM-5 realiza la deshidratación de metanol dada su función ácida. En este trabajo se comparan dos métodos de preparación del catalizador bifuncional; por síntesis sucesiva (catalizador con el nombre CuO-ZnO/S-HZSM-5) y por mezcla física (catalizador con el nombre CuO-ZnO/HZSM-5). Para ello, primero se preparó y se caracterizó CuO-ZnO, HZSM-5 y silicalita. En la preparación del catalizador bifuncional CuO-ZnO/S-HZSM-5 se incorporó silicalita (S) para favorecer el crecimiento de cristales con estructura tipo MFI ((Zeolite Socony Mobil - FIVE). Todos los catalizadores fueron caracterizados mediante las técnicas de difracción de rayos X, reducción a temperatura programada y desorción de NH3 a temperatura programada. La cristalinidad de CuO en los catalizadores CuO-ZnO, CuO-ZnO/S-HZSM-5 y CuO-ZnO-HZSM-5 fue de 67%, 49% y 64%, respectivamente. La temperatura máxima de reducción encontrada para el CuO-ZnO/S-HZSM-5 fue de 306°C, que difiere del catalizador bifuncional por mezcla física CuO-ZnO-HZSM-5 que fue de 282°C, este cambio tiene relación con la cristalinidad de CuO, a menor cristalinidad de CuO; mayor su temperatura de reducción. El catalizador CuO-ZnO/S-HZSM-5 presenta una acidez de Brönsted igual a 0,37mol NH3/kg comparable con la acidez de zeolita pura HZSM-5 (0,41mol NH3/kg), mientras el catalizador CuO-ZnO-HZSM-5 tiene una acidez de Brönsted menor, igual a 0,25mol NH3/kg.
The effect of the acid pre-treatment temperature of natural diatomaceous earth on the Si/Al ratio of ZSM-5 zeolite
(National University of Colombia, 2023) Ronald M. Lara Prado; Luis Lopez N; Saúl Cabrera M.
Bolivian diatomaceous earth is a potentially lower cost silica source than conventional high purity reagents used in zeolite synthesis. Due to its complex composition, it is necessary to pre-treat it with sulfuric acid in order to reduce impurities and regulate the aluminum content. In the present work several experiments were carried out with natural Bolivian diatomaceous earth in the pre-treatment stage. In order to determine the effect on the final Si/Al ratio, the temperature of the acid pre-treatment was varied between 50 to 155 °C. The results show that the Si/Al ratio can be modulated from 6.2 up to 38.1. These treated diatomaceous earth samples were used to synthetise ZSM-5 zeolite. The obtained ZSM-5 zeolites have a Si/Al ratio in the following range: 9.6 to 40.2. XRD, NH3-TPD and Nitrogen Physisorption techniques were used to characterise the properties of the obtained zeolites. The degree of crystallisation and the specific surface area are directly related to the Si/Al ratio, resulting in high values at high Si/Al ratios. The acid sites are composed of strong Brönsted acid sites and, strong and weak Lewis acid sites. For the zeolite with a low Si/Al ratio a high total acidity was found (>0.51 molNH3/Kgzeolite), while at high Si/Al ratios the total acidity is reduced (<0.38 molNH3/Kgzeolite).