Innovative flow-through reaction system for the sustainable production of phenolic monomers from lignocellulose catalyzed by supported Mo2C.

Molybdenum carbide supported on activated carbon (ß-Mo2C/AC) has been tested as catalyst in the reductive catalytic fractionation (RCF) of lignocellulosic biomass both in batch and in Flow-Through (FT) reaction systems. High phenolic monomer yields (34 wt.%) and selectivity to monomers with reduced side alkyl chains (up to 80 wt.%) could be achieved in batch in the presence of hydrogen. FT-RCF were made with no hydrogen feed, thus via transfer hydrogenation from ethanol. Similar selectivity could be attained in FT-RCF using high catalyst/biomass ratios (0.6) and high molybdenum loading (35 wt.%) in the catalyst, although selectivity decreased with lower catalyst/biomass ratios or molybdenum contents. Regardless of these parameters, high delignification of the lignocellulosic biomass and similar monomer yields were observed in the FT mode (13-15 wt.%) while preserving the holocellulose fractions in the delignified pulp. FT-RCF system outperforms the batch reaction mode in the absence of hydrogen, both in terms of activity and selectivity to reduced monomers that is attributed to the two-step non-equilibrium processes and the removal of diffusional limitations that occur in the FT mode. Even though some molybdenum leaching was detected, the catalytic performance could be maintained with negligible loss of activity or selectivity for 15 consecutive runs.

Exploring a Low-Cost Valorization Route for Amazonian Cocoa Pod Husks through Thermochemical and Catalytic Upgrading of Pyrolysis Vapors.

Ecuador as an international leader in the production of cocoa beans produced more than 300 000 tons in 2021; hence, the management and valorization of the 2 MM tons of waste generated annually by this industry have a strategic and socioeconomic value. Consequently, appropriate technologies to avoid environmental problems and promote sustainable development and the bioeconomy, especially considering that this is a megadiverse country, are of the utmost relevance. For this reason, we explored a low-cost pyrolysis route for valorizing cocoa pod husks from Ecuador's Amazonian region, aiming at producing pyrolysis liquids (bio-oil), biochar, and gas as an alternative chemical source from cocoa residues in the absence of hydrogen. Downstream catalytic processing of hot pyrolysis vapors using Mo- and/or Ni-based catalysts and standalone γ-Al2O3 was applied for obtaining upgraded bio-oils in a laboratory-scale fixed bed reactor, at 500 °C in a N2 atmosphere. As a result, bimetallic catalysts increased the bio-oil aqueous phase yield by 6.6%, at the expense of the organic phase due to cracking reactions according to nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS) results. Overall product yield remained constant, in comparison to pyrolysis without any downstream catalytic treatment (bio-oil ∼39.0-40.0 wt % and permanent gases 24.6-26.6 wt %). Ex situ reduced and passivated MoNi/γ-Al2O3 led to the lowest organic phase and highest aqueous phase yields. The product distribution between the two liquid phases was also modified by the catalytic upgrading experiments carried out, according to heteronuclear single-quantum correlation (HSQC), total correlation spectroscopy (TOCSY), and NMR analyses. The detailed composition distribution reported here shows the chemical production potential of this residue and serves as a starting point for subsequent valorizing technologies and/or processes in the food and nonfood industry beneficiating society, environment, economy, and research.

Co-pyrolysis of sewage sludge and manure.

The management and valorization of residual organic matter, such as sewage sludge and manure, is gaining interest because of the increasing volume of these residues, their localized generation and the related problems. The anaerobic digestion of mixtures of sewage sludge and manure could be performed due to the similarities between both residues. The purpose of this study is to evaluate the feasibility of the co-pyrolysis of sewage sludge (SS) and digested manure (DM) as a potential management technology for these residues. Pyrolysis of a sewage sludge/manure blend (50:50%) was performed at 525°C in a stirred batch reactor under N2 atmosphere. The product yields and some characteristics of the product were analyzed and compared to the results obtained in the pyrolysis of pure residues. Potential synergetic and antagonist effects during the co-pyrolysis process were evaluated. Although sewage sludge and manure seem similar in nature, there are differences in their pyrolysis product properties and distribution due to their distinct ash and organic matter composition. For the co-pyrolysis of SS and DM, the product yields did not show noticeable synergistic effects with the exception of the yields of organic compounds, being slightly higher than the predicted average, and the H2 yield, being lower than expected. Co-pyrolysis of SS and DM could be a feasible management alternative for these residues in locations where both residues are generated, since the benefits and the drawbacks of the co-pyrolysis are similar to those of the pyrolysis of each residue.