Promoting light hydrocarbons yield by catalytic hydrodechlorination of residual chloromethanes using palladium supported on zeolite catalysts

Gas catalytic hydrodechlorination (HDC) of trichloromethane (TCM) and dichloromethane (DCM) was analyzed using Pd (1 wt.%) on different zeolites as catalysts. The aim of this study was to know the surface properties of the catalysts and reaction conditions that promote the yield to light hydrocarbons in this reaction. Five different zeolite supports were used from three commercial zeolites (KL, L-type; NaY, Faujasite; H-MOR, Mordenite). KL and NaY were submitted to ionic exchange treatments in order to increase their acidity and analyze the effect of the acidity in the activity and selectivity of the HDC reaction. Exchanged zeolites (HL and HY) showed the highest Pd dispersion due to their higher surface acidity. The best TCM/DCM conversion and selectivity to light hydrocarbons was obtained using the two non-exchanged zeolite-catalysts, KL and NaY. Low surface acidity seems to be the key aspect to promote the formation of light hydrocarbons. The formation of these products is favored at high reaction temperatures and low H2: chloromethane ratios. KL showed the highest selectivity to olefins (60%), although with a lower dechlorination degree. Non-exchanged NaY catalyst showed high selectivity to paraffins (70% and 95% for the HDC of DCM and TCM, respectively)Authors gratefully acknowledge financial support from FEDER/Ministerio de Ciencia, Innovación y Universidades—Agencia Estatal de Investigación/ CTM2017-85498-R. C. Fernández Ruiz acknowledges MINECO for his research gran

Enhanced activity of carbon-supported Pd-Pt catalysts in the hydrodechlorination of dichloromethane

Monometallic and bimetallic catalysts with different proportions of Pd and Pt prepared by co-impregnation on activated carbon have been deeply characterized by inductively coupled plasma-mass spectroscopy, temperature-programmed reduction, 77K N2 adsorption-desorption, CO chemisorption, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. They have been tested in the gas-phase hydrodechlorination of dichloromethane (DCM) at atmospheric pressure, reaction temperatures of 150-200°C, and a space-time of 0.6kghmol-1. The presence of Pd and Pt in the catalysts produces a synergistic effect observed in terms of dichloromethane conversion and overall dechlorination, especially when both metals are in similar proportions. The results from catalysts characterization suggest that the enhanced activity is due to a significant decrease of the metallic particles size and an optimum ratio of electro-deficient to zero-valent species in the bimetallic catalysts. The catalyst with 0.90wt.% of Pt and 0.50wt.% of Pd yielded the best results. Under intensified conditions, viz. 250°C and 1.73kghmol-1, 100% DCM conversion and 98.6% overall dechlorination were obtained. This catalyst had most of its metallic particles within the range of 0.5-1nmThe authors gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad through the project CTM2011-28352. M. Martín Martínez acknowledges the Spanish Ministerio de Ciencia e Innovación and the European Social Fund for her research grant (BES 2009-016802

Removal of chlorinated organic volatile compounds by gas phase adsorption with activated carbon

This paper discusses the removal of chlorinated volatile organic compounds (Cl-VOCs) from gas streams by means of fixed-bed adsorption with a commercial activated carbon (AC). Column experiments were performed at different conditions (inlet concentration, temperature, pressure, gas flow rate and bed length). A two-parameter model introduced by Yoon and Nelson was applied to predict the entire breakthrough curves for chloromethane adsorption. Complete regeneration of the exhausted AC was performed at mild conditions (atmospheric pressure and room temperature). In order to gain a better knowledge on the effect of the surface chemistry of AC on the adsorption of Cl-VOCs, the quantum-chemical COSMO-RS method was used to simulate the interactions between AC surface groups and different Cl-VOCs as monochloromethane, dichloromethane and trichloromethane. This information can be useful for tailoring the ACs with the objective of improving their adsorption capacities by further functionalization. To confirm this, the commercial AC tested was modified by means of different thermal and oxidative treatments (nitric acid and ammonium persulfate), being the surface chemistry and textural properties of the resulting materials characterized by different techniques. The modified ACs were then tested in column adsorption experiment with different Cl-VOCs. The uptake of these compounds increased with the basic character of the AC surfaceThe authors are grateful to the Spanish “Ministerio de Ciencia e Innovación (MICINN)” and “Comunidad de Madrid” for financial support (Projects CTQ2011-26758, CTQ2009-09983 and S2009/PPQ-1545

Kinetic study of the hydrodechlorination of chloromethanes with activated-carbon-supported metallic catalysts

This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Industrial and Engineering Chemistry Research, copyright © American Chemical Society after peer review. To access the final edited and published work, see http://pubs.acs.org/doi/abs/10.1021/ie5042484The kinetics of the hydrodechlorination (HDC) of dichloromethane (DCM) and chloroform (TCM) with Pd, Pt, Rh, and Ru on activated carbon catalysts has been studied at temperatures between 100 and 250 °C. Different kinetic models have been checked, namely, pseudo-first-order and Langmuir-Hinshelwood-Hougen-Watson (LHHW) with adsorption, chemical reaction, or desorption control. The HDC of DCM and TCM with the Pd and Pt catalysts was well-described by the LHHW model with reactant adsorption as the rate-controlling step. However, with Rh and Ru catalysts, chemical reaction and desorption of the reaction products appear to be the rate-controlling steps in the HDC of DCM and TCM, respectively. In this last case, different sets of complex reactions seem to occur on the surface of the catalyst depending on the temperature, preventing determination of a confident value of the activation energy, because of the formation of oligomeric coke-like deposits and the subsequent severe deactivation of these catalysts. The corresponding kinetic parameters for the proposed models have been calculatedThe authors gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) through the project CTM2011-28352. M. Martín Martínez and A. Arévalo Bastante acknowledges the Spanish Ministerio de Ciencia e nnovación (MICINN) and the European Social Fund for her research gran

Gas-phase hydrodechlorination of mixtures of chloromethanes with activated carbon-supported platinum catalysts

Platinum catalysts supported on activated carbon (Pt/C) at different metal loadings (0.5-2% Pt) have been tested in the gas-phase hydrodechlorination (HDC) of mixtures of dichloromethane (DCM) and chloroform (TCM), with a total feed concentration of 1000ppmv. Almost complete dechlorination was achieved at 250°C, 1kghmol-1 space time and a H2/CM molar ratio of 25 with the 2% Pt catalyst. At a reaction temperature of 250°C, scarce inhibition in the conversion of both compounds was observed compared to the HDC of the individual chloromethanes. The TOF values for DCM increase with the Pt content, which can be attributed to the higher proportion of the zero-valent species. The selectivity to reaction products suggests a parallel reactions scheme. The catalysts showed a high stability, demonstrated by the unchanged conversion of both chloromethanes upon time on stream in long-term experiments carried out at up to 26h.The authors gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) through the project CTM2011-2835

Impact of targeting MYC in metabolic reprogramming and differentiation of cancer

Alterations in several metabolic pathways due to increased energy and biomass demand, as consequence of the uncontrolled proliferation of cancer cells, is known as metabolic reprogramming. Mutations in tumor suppressor genes and oncogenes that initiate cancer development, are responsible directly and indirectly of the changes in major cellular energy production processes, including glycolysis, glutaminolysis, and lipid metabolism. Neuroblastoma (NB) is a solid tumor that develops extracranially in the sympathetic nervous system, and the most diagnosed cancer during the first year of life. Among several genetic alterations, MYCN-amplification occurs in approximately 25% of all cases, associated with poor survival rate. Although the MYCN protein plays a crucial role in NB progression, no inhibitors have been approved for clinical use, as targeting MYCN has proven to be challenging. Thus, other indirect strategies, such as targeting downstream processes controlled by MYCN including metabolism and differentiation, represent alternatives to overcome the drawbacks of directly targeting this oncoprotein. In clear cell renal cell carcinoma (ccRCC), loss of the von Hippel-Lindau (VHL) gene provokes constitutive activation of hypoxia inducible factors (HIFs). Due to disruptions in a myriad of metabolic pathways, and in part, as consequence of the continuous stabilization of HIFs, ccRCC is considered a metabolic disease. Moreover, although MYC amplification is found only in 5-10 % of the cases, increased MYC signaling has been associated with development of aggressive forms of ccRCC. In paper I we investigated the metabolic changes induced by MYCN amplification in NB. By combining proteomics, transcriptome analysis and functional metabolic assays, we demonstrated that MYCN induced changes in several metabolic enzymes, increasing glycolysis and oxidative phosphorylation. We also found that fatty acids were the preferred mitochondrial fuel for energy production in MYCN-amplified cells. Moreover, data from tracing experiments with 13C-labeled glucose or glutamine indicated that MYCN-amplified NB cells synthetized glutamine de novo. Furthermore, targeting fatty acid oxidation resulted in reduction of viability in NB cells with MYCN-amplification in vitro and in reduction of tumor burden in vivo. Since we found that fatty acid oxidation was relevant for MYCN-amplified NB, we further studied the effects of inhibiting de novo fatty acids synthesis in paper II. Using five different inhibitors targeting two consecutive enzymes in the process, we described that inhibition of the synthesis of fatty acids resulted in striking neuronal differentiation associated with activation of ERK signaling, and reduction of MYCN and MYC levels. Moreover, lipid composition as well as mitochondrial function and morphology of NB cells was altered. In addition, fatty acid synthesis inhibition led to reduced tumor formation and increased differentiation markers in several NB xenograft models. Together, the results in paper I and II suggested that targeting lipid metabolism could be a potential therapeutic approach for NB patients. In paper III we further analyzed the potential differentiation of NB cells induced by activation of nuclear hormone receptors (NHRs). Our data showed that the simultaneous activation of glucocorticoid receptor (GR), estrogen receptor α (ERα) and retinoic acid receptor α (RARα) potentiated neurite outgrowth, induced changes in the glycolytic and mitochondrial functions, accompanied with lipid droplet accumulation, and reduced proliferation in vitro as well as tumor burden in vivo. In addition, single cell nuclei analysis revealed a sequential expression of the three NHRs during adrenal gland development. Notably, in silico analysis of patient cohorts demonstrated that high expression of these NHRs were correlated with better overall survival. Thus, combination therapy with the concurrent activation of GR, ERα and RARα represents a promising strategy to induce differentiation in NB patients. Paper IV describes the mechanism behind lipid droplet (LD) accumulation induced by MYC inhibition during hypoxia in clear cell renal cell carcinoma (ccRCC). We found that HIF expression together with MYC inhibition resulted in LD deposition. Our results showed that due to HIF stabilization, glutamine-derived carbons were directed for synthesis of fatty acids, further accumulating in LDs. Importantly, we identified that the hypoxia inducible lipid droplet associated (HILPDA) gene, was overexpressed upon HIF induction and MYC inhibition, controlling LD formation in ccRCC cells. Hence, our study characterizes the molecular mechanism of LD accumulation in relation to hypoxia and MYC signaling, providing new understanding of metabolic adaption in ccRCC. Altogether, the data compiled in this thesis describes the important role of the MYC family of proteins in differentiation and metabolism of NB and in the metabolic reprogramming of ccRCC providing new knowledge and potential targets for development of novel therapeutic approaches

Numerical study of the behaviour of wings under different flight conditions

The project consists on the numerical analysis of wings to support all loads during flight phases. The A340 600 wing is taken to perform a numerical aerodynamic analysis to obtain the desired flight loads through 3D Panel Method with XFLR5 tool and then numerical structural analysis to study failure criteria, and maximum vertical displacement of the wing when it is used different materials and different thicknesses at any of the different flight phases, through Finite Element Method using Abaqus/CAE software. After that, it is performed an optimization so that it can be obtained a lighter wing that do not fracture, buckles or cracks. This optimization also allows to reduce costs.Ingeniería Aeroespacia

Valorization of chloromethanes by hydrodechlorination with metallic catalysts

The performance of Pd, Pt, Rh and Ru based catalysts in the hydrodechlorination of chloromethanes to obtain ethane and ethylene was evaluated by means of computational analysis and hydrodechlorination experiments. A computational analysis using density functional theory (DFT) was developed to obtain preliminary insight on the potential catalytic mechanisms for the reactions involved using palladium, platinum, rhodium and ruthenium metallic clusters. Stable catalytic intermediates were obtained by quantum-chemical calculations in the hydrodechlorination of dichloromethane on Pd6and Rh6clusters, presenting [rad][rad]CH2and [rad]CH3radicals and C2H4, C2H6and CH4products. On the contrary, it was not possible to obtain all these stable intermediates using Pt6and Ru6clusters. Theoretical analysis revealed lower desorption energies for ethane and ethylene products in Pd6than in Rh6clusters, what indicates a favorable selectivity of Pd-based catalyst for desired C2products. Then, carbon supported catalysts containing these four metals were prepared and experimentally evaluated in the hydrodechlorination of dichloromethane (DCM) and trichloromethane (TCM) at low H2excess and a reaction temperature range of 150-400 °C. In agreement with computational results, in experimental tests, the Pd based catalyst showed the best performance for the hydrodechlorination of chloromethanes to obtain C2products, followed by Rh, Ru and Pt have a poor performance, in special Pt based catalyst, which shows almost no selectivity to C2products. This computational and experimental study emphasizes, for the first time, the good performance (high activity and selectivity) of Pd carbon supported catalysts in the valorization of chloromethane compounds to obtain C2hydrocarbon productsThe authors gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) through the project CTM 2014-53008 and to the “Centro de Computación Científica de la Universidad Autónoma de Madrid” for computational facilitie

Effect of the Pt–Pd molar ratio in bimetallic catalysts supported on sulfated zirconia on the gas-phase hydrodechlorination of chloromethanes

Bimetallic Pt:Pd catalysts with different molar ratios and 0.5 wt.% overall metal load supported on sulfated zirconia catalysts were synthesized and tested in the gas-phase hydrodechlorination (HDC) of chloromethanes and their mixtures. The catalysts were characterized by adsorption–desorption of N2 at −196 °C, X-ray diffraction, X-ray photoelectronic spectroscopy, temperature-programmed reduction, and aberration-corrected scanning transmission electron microscopy (STEM). The effect of the Pt:Pd molar ratio on the activity, stability, and selectivity was analyzed. The high acidity of the sulfated zirconia results in metal particles of small size (mainly <5 nm), as confirmed by STEM. The bimetallic catalysts showed higher stability than the monometallic ones, as demonstrated in long-term experiments (80 h on stream), confirming the positive effect of combining the two metallic phases. Turnover frequency (TOF) values in the range 0.0007–0.0168 s−1 and apparent activation energies between ≈41 and 44 kJ·mol−1 were obtained. TOF values for dichloromethane HDC increased with increasing mean metal particle size within the range of this work (≈1.2–2.3 nm). The catalysts with Pt:Pd molar ratios of 1:3 and 1:1 showed significantly better performance than the 3:1 one for overall dechlorination due to their higher atomic metal content and TOF at the same total metal weight load (0.5%)The authors are grateful to the Spanish ‘‘Ministerio de Economíay Competitividad (MINECO)” for financial support (ProjectsCTM2011-28352 and CTM2014-53008-