Catalytic reforming of nitrogen-containing volatiles evolved through pyrolysis of composted pig manure

Insight into the Ex Situ Catalytic Pyrolysis of Biomass over Char Supported Metals Catalyst: Syngas Production and Tar Decomposition

Ex situ catalytic pyrolysis of biomass using char-supported nanoparticles metals (Fe and Ni) catalyst for syngas production and tar decomposition was investigated. The characterizations of fresh Fe-Ni/char catalysts were determined by TGA, SEM–EDS, Brunauer–Emmett–Teller (BET), and XPS. The results indicated that nanoparticles metal substances (Fe and Ni) successfully impregnated into the char support and increased the thermal stability of Fe-Ni/char. Fe-Ni/char catalyst exhibited relatively superior catalytic performance, where the syngas yield and the molar ratio of H2/CO were 0.91 Nm3/kg biomass and 1.64, respectively. Moreover, the lowest tar yield (43.21 g/kg biomass) and the highest tar catalytic conversion efficiency (84.97 wt.%) were also obtained under the condition of Ni/char. Ultimate analysis and GC–MS were employed to analyze the characterization of tar, and the results indicated that the percentage of aromatic hydrocarbons appreciably increased with the significantly decrease in oxygenated compounds and nitrogenous compounds, especially in Fe-Ni/char catalyst, when compared with no catalyst pyrolysis. After catalytic pyrolysis, XPS was employed to investigate the surface valence states of the characteristic elements in the catalysts. The results indicated that the metallic oxides (Me_xO_y) were reduced to metallic Me⁰ as active sites for tar catalytic pyrolysis. The main reactions pathway involved during ex situ catalytic pyrolysis of biomass based on char-supported catalyst was proposed. These findings indicate that char has the potential to be used as an efficient and low-cost catalyst toward biomass pyrolysis for syngas production and tar decomposition.

Thermochemical conversion of cobalt-loaded spent coffee grounds for production of energy resource and environmental catalyst

Thermochemical conversion of cobalt (Co)-loaded lignin-rich spent coffee grounds (COSCG) was carried out to find the appropriate pyrolytic conditions (atmospheric gas and pyrolytic time) for syngas production (H₂ and CO) and fabricate Co-biochar catalyst (CBC) in one step. The use of CO₂ as atmospheric gas and 110-min pyrolytic time was optimal for generation of H₂ (∼1.6 mol% in non-isothermal pyrolysis for 50 min) and CO (∼4.7 mol% in isothermal pyrolysis for 60 min) during thermochemical process of COSCG. The physicochemical properties of CBC fabricated using optimized pyrolytic conditions for syngas production were scrutinized using various analytical instruments (FE-SEM, TEM, XRD, and XPS). The characterizations exhibited that the catalyst consisted of metallic Co and surface wrinkled carbon layers. As a case study, the catalytic capability of CBC was tested by reducing p-nitrophenol (PNP), and the reaction kinetics of PNP in the presence of CBC was measured from 0.04 to 0.12 s^-1.

Characterization of pig manure-derived hydrochars for their potential application as fertilizer

In China, intensive pig farming has led to serious environmental issues with the need to dispose off large quantities of pig manure. Chinese agriculture relies on high inputs of chemical fertilizers leading to gradual decreasing organic matter contents in many arable soils. We propose that hydrochars produced from pig manure could potentially replace chemical fertilizers and, at the same time, resolve the waste disposal problem. The hydrochars used in this study were produced from pig manure at five different pyrolysis temperatures ranging between 160 and 240 °C and three residence times (1, 5, and 8 h). All hydrochars were assessed for composition of major elements. Results showed that the yield and organic matter (OM) contents in hydrochars were 50-74% and 40-56%, respectively. The concentrations of total nitrogen (N), potassium (K₂O), and OM in the hydrochar decreased, whereas contents of phosphorus (P₂O₅), copper (Cu), and zinc (Zn) increased with increasing reaction temperature and time. Hydrothermal carbonization of pig manure is a rapid method for transforming pig manure into an organic fertilizer, but it is necessary to assess the potential soil contamination risk of Cu and Zn for the pig manure hydrochar as organic fertilizer.

Catalytic gasification of oil-extracted residue biomass of Botryococcus braunii

Catalytic gasification of the oil-extracted residue biomass of Botryococcus braunii was demonstrated in a laboratory-scale continuous feeding dual bed reactor. Steam gasification at 1023 K over Ni-Fe/Mg/Al catalyst can completely reform tar derived from pyrolysis of the residue biomass into C1 gases and hydrogen, and has achieved 91%-C conversion to gaseous product (CO+CO2+CH4). Composition of product gas has higher contents of CO and H2 with their ratio (H2/CO) of around 2.4 which is slightly H2-rich syngas. Maximum hydrogen yield of 74.7 mmol g-biomass(-1) obtained in this work is much higher than that from gasification of other algal biomass reported in literature. The residue biomass of B. braunii can be a superior renewable source of syngas or hydrogen.

Pyrolysis characteristics and kinetic analysis of different dewatered sludge

Pyrolysis behavior and kinetic properties of four different sludge, including raw sludge and three sludge respectively dewatered with FeCl3/CaO, FeCl3/CaO/coal and Fenton's reagent (Fe(2+)+H2O2)/CaO, were analyzed by using thermogravimetry coupled with Fourier transform infrared spectrometry (TG-FTIR). The results show that organics of raw sludge mainly decomposed at 378-676K, and the decomposition temperature of conditioned sludge was prolonged to 823K. Addition of coal and catalysis of CaO/ferric salt both promoted sludge pyrolysis, leading to more NH3, CH4 and CO productions. Compared with dry sludge, wet sludge pyrolysis was hard to finish completely, and the first peak of organics' decomposition appeared at higher temperature (about 573K). Additionally, the global reaction model was suited to determine kinetic parameters, which showed that dry sludge conditioned with more CaO addition had higher E values than those of dry raw sludge. Opposite results were obtained when sludge samples were wet.