Mesoporous Activated Carbon Supported Ru Catalysts to Efficiently Convert Cellulose into Sorbitol by Hydrolytic Hydrogenation

Catalysts consisting of Ru nanoparticles (1 wt%), supported on mesoporous activated carbons (ACs), were prepared and used in the one-pot hydrolytic hydrogenation of cellulose to obtain sorbitol. The carbon materials used as supports are a pristine commercial mesoporous AC (named SA), and two samples derived from it by sulfonation or oxidation treatments (named SASu and SAS, respectively). The catalysts have been thoroughly characterized regarding both surface chemistry and porosity, as well as Ru electronic state and particle size. The amount and type of surface functional groups in the carbon materials becomes modified as a result of the Ru incorporation process, while a high mesopore volume is preserved upon functionalization and Ru incorporation. The prepared catalysts have shown to be very active, with cellulose conversion close to 50% and selectivity to sorbitol above 75%. The support functionalization does not lead to an improvement of the catalysts’ behavior and, in fact, the Ru/SA catalyst is the most effective one, with about 50% yield to sorbitol, and a very low generation of by-products.This research was funded by Spanish Ministry of Science, Innovation and Universities and FEDER, project of reference RTI2018-095291-B-I00, GV/FEDER (PROMETEO/2018/076) and University of Alicante (VIGROB-136)

Carbon-Black-Supported Ru Catalysts for the Valorization of Cellulose through Hydrolytic Hydrogenation

The one-pot hydrolytic hydrogenation of cellulose (HHC) with heterogeneous catalysts is an interesting method for the synthesis of fuels and chemicals from a renewable resource like lignocellulosic biomass. Supported metal catalysts are interesting for this application because they can contain the required active sites for the two catalytic steps of the HHC reaction (hydrolysis and hydrogenation). In this work, Ru catalysts have been prepared using a commercial carbon black that has been modified by sulfonation and oxidation treatments with H2SO4 and (NH4)S2O8, respectively, in order to create acidic surface sites. The correlation between the catalysts’ properties and catalytic activity has been addressed after detailed catalyst characterization. The prepared catalysts are active for cellulose conversion, being that prepared with the carbon black treated with sulfuric acid the most selective to sorbitol (above 40%). This good behavior can be mainly explained by the suitable porous structure and surface chemistry of the carbon support together with the low content of residual chlorine.This work was possible thanks to the funding received from the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER, project of reference CTQ2015-66080-R, GV/FEDER (PROMETEO/2018/076) and University of Alicante (VIGROB-136)

Catalytic conversion of cellulose and biomass into high added-value chemicals using carbon materials and Ru catalysts

La presente Tesis Doctoral se ha centrado en el uso de materiales lignocelulósicos como materia prima renovable para la generación de biocombustibles y productos químicos de alto valor añadido. Para ello, se ha investigado la conversión catalítica de biomasa en alcoholes C6 mediante hidrogenación hidrolítica empleando catalizadores novedosos, basados en materiales carbonosos y rutenio. Los objetivos propuestos en este estudio, incluyendo profundizar en la comprensión del proceso, analizar su rendimiento catalítico y estudiar algunos parámetros que influyen en la selectividad y la conversión con el fin de mejorarlos

Cellulose hydrolysis catalysed by mesoporous activated carbons functionalized under mild conditions

The catalytic hydrolysis of cellulose allows the transformation of this sustainable and renewable raw material to obtain biofuels and high-added value chemicals. The process requires acidic catalysts, which should be preferably solid in order to make it greener and, thus, this work proposes the use of functionalized carbon materials for such an application. A mesoporous commercial carbon of trade name SA-30, abbreviated as SA in this work, has been chemically treated at room temperature to create acidic surface oxygen functional groups. The prepared carbon catalysts have been thoroughly characterized by N2 adsorption-desorption at − 196 ºC, temperature programmed desorption and X-ray photoelectron spectroscopy. SAS carbon (prepared by treatment with a saturated solution of (NH4)2S2O8 in 1 M H2SO4 and named by adding S to the name of the original carbon) is the most effective of the studied catalysts. It allows achieving high cellulose conversion (about 61%) and glucose selectivity. Thus, the low-cost functionalized carbons prepared at mild conditions are effective and promising catalysts for the transformation of cellulose into glucose.The authors thank Ministerio de Ciencia, Innovación y Universidades (RTI2018-095291-B-I00), GV/FEDER (PROMETEOII/2014/010) and University of Alicante (VIGROB-136) for financial support. F.-Z. Azar thanks the AECID (research scholarship for development (2015/2016)) and University of Alicante (cooperation programs for development) for financial support

Direct cost-efficient hydrothermal conversion of Amazonian lignocellulosic biomass residue

The transformation of non-edible lignocellulosic biomass into high added-value chemicals and biofuels associated with lower energy process requirements is a promising strategy for meeting the actual demands of clean energy. Here, we report the study of the non-catalytic conversion of biomass wastes issued from two Amazonian abundant fruits (cupuaçu shell and assai stone) into liquid valuable chemicals. The parent biomass samples were first comprehensively characterized using TG, XRD, and FTIR; then, they were pretreated by ball milling and by chemical processing in ionic liquid, and finally, they were hydrothermally treated to be converted into chemical products benefiting from their hemicellulose and cellulose contents. The results revealed the importance of the pretreatments in the conversion rate, while the selectivity into main chemical products (such glucose, HFM, furfural, xylose) is not affected by the pretreatments neither physical nor chemical ones. The conversion of both biomasses and their products’ distribution were comprehensively discussed, with the highest conversion obtained using assai stone biomass (90%). This study could pave the way for investigating the non-catalytic route of biomass conversion, as a lesser energy process, resulting in a cost-effective conversion process.This work was supported by the national and regional Spanish governments (RTI2018–095291-B-100, PID2021–123079OB-I00 project funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe (European Union) and CIPROM/2021/070) (Generalitat Valenciana) and the University of Alicante (VIGROB-136)

Potential reuse of sludge from a potable water treatment plant in Al Hoceima city in northern Morocco

Producing potable water generates a large amount of sludge, which consumes energy and must be managed and controlled. A case study of a potable water production plant in Al Hoceima City in northern Morocco is described here. The plant produces 15000 ​m3 of potable water each day to meet the water demand of Al Hoceima City, and this causes 3 ​t of sludge to be produced each day. Sludge extracted while producing potable water was characterized, and the possibility of reusing the sludge rather than disposing of it directly to the environment was assessed. The pH, turbidity, aluminum content, and other characteristics of the sludge were determined. Jar tests were performed to determine the optimum coagulant (aluminum sulfate) dose to ensure that the minimum required amount of aluminum sulfate was used. The characterization results indicated that the sludge was stable and reusable. The jar-test results allowed the amount of coagulant used to be optimized and will lead to markedly less sludge being disposed of than is currently the case