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Pyrolysis is a clean and economical method to dispose meat and bone meal (MBM) from animal carcasses. However, the large quantity of nitrogen from the animal protein will lead to the formation of gaseous-N compounds such as NH 3 and HCN, which are the precursors of NOx. In this study, the release behavior of these gaseous-N compounds during the pyrolysis of MBM was investigated using a temperature-programed tube reactor combined with an FTIR analyzer. Moreover, the formation mechanism of them was elucidated by examining the evolution of solid and liquid N-products with temperature. The result showed that 31.0% of the MBM was released as gaseous N including NH 3 , HCN and HNCO, among which NH 3 accounted for 76.2% while HNCO was a minor product. NH 3 was mainly released below 300 °C from the decomposition of ammonium and the polymerization of liable protein. On the other side, the nitriles and heterocyclic N-compounds identified in tar and char were the precursors of HCN and HNCO. The results provided basic data for the inhibition and removal of gaseous N-compounds during the pyrolysis of animal biomass. [ABSTRACT FROM AUTHOR]

Pyrolysis of digestate from anaerobic digestion of kitchen waste yielded combustible gas and liquid with biochar as solid product. In this study, the pyrolysis characterization of the digestate and the P availability of the obtained pyrochar were discussed. Thermogravimetry (TG) analysis showed that 15.56 % of the weight loss occurred from 600 °C to 750 °C due to CaCO 3 decomposition. When the final temperature increased from 500 °C to 700 °C, the HHV of pyrogas was slightly affected elevated from 17.20 MJ/Nm3 to 18.12 MJ/Nm3, while the relative content of polycyclic aromatic hydrocarbons (PAHs) in the liquid raised from 1.36 % to 6.28 %. SMT analysis showed that phosphorus in the pyrochar was fully converted to apatite phosphorus (AP) due to an excessive Ca content. Neutral ammonia citrate (NAC) extraction indicated that the availability of P in pyrochar was significantly decreased from 7.97 mg/g at 500 °C to 2.29 mg/g at 700 °C. Overall, the results showed that pyrolysis at 500 °C was suitable to obtain high-quality fuel and pyrochar with high P availability. [Display omitted] • The gas and liquid products from kitchen waste digestate pyrolysis are analyzed. • OP and NAIP in digestate is almost transformed into AP after pyrolysis. • The NACP content in pyrochar achieves its highest value when pyrolyzed at 500 °C. [ABSTRACT FROM AUTHOR]

Highlights • Mechanical properties of waste papers are closely correlated with devolatilization. • Start of devolatilization caused a sudden decrease in relative storage modulus ( E ′ r). • Kinetics of storage modulus change is investigated referring to activation energy. • E ′ r can be predicted with mass loss ratio and CO 2 emission. Abstract This article details a correlation study on early devolatilization behaviors (drying & volatile emission at 25–240 °C) and the change in mechanical properties (expressed by viscoelasticity) of four types of waste papers. The early stage of devolatilization was investigated using the TG-FTIR and mechanical properties using the dynamic mechanical analysis (DMA) method. The results show that the elastic and viscous mechanical properties showed obvious correlations with free and bound water evaporation and volatile emission. The storage modulus (E ′) and loss modulus (E ″) of the papers decreased as temperature increased and at the two important temperatures, namely 100 °C, the start of bound water evaporation, and 150 °C, the start of devolatilization in TG & DTG curves, E ′ showed extrema. Especially the relative storage modulus ( E ′ r) exhibited a sudden decrease at around 150 °C, where the activation energy of thermochemical conversion jumps from low values to high values, indicating the start of devolatilization. CO 2 is the major compound of the volatiles and it is well correlated with E ′ r in exponential function model and can be used as an index for predicting the E ′ r of the waste papers in their early devolatilization stage; while during the drying stage, mass loss ratio can be used to predict E ′ r of the waste papers. [ABSTRACT FROM AUTHOR]

The pyrochar of sewage sludge can be exploited for catalytic tar reforming since the developed pore structure and high metal content. However, Fe in the raw sludge tends to form Fe-S and Fe-P during pyrolysis, which inhibits catalytic activity of pyrochar. Here, the wet sludge was conditioned with quicklime, and the pyrochar was used to reform sewage sludge pyrolysis volatiles. The results showed that H 2 generation from pyrochar reforming increased by 55.2% after conditioning. In addition, the tar elimination achieved the highest ratio (79.6%) compared with unconditioned char and quicklime, while PAHs and N-compounds were concentrated in tar with the relative content 46.9% and 37.1% due to the significant removal of other tar compounds such as oxygenates. During pyrolysis, a proportion of added CaO captured P and S anions which favored the formation of Ca 2 Fe 2 O 5 and Fe-O, while the remaining CaO (21.9%) was highly dispersed on pyrochar. This promoted both the catalytic tar cracking effects and the CO 2 absorption of the char. These findings provide a novel method to produce H 2 -rich gas from sewage sludge pyrolysis with less tar yield. • The reforming of volatile from sewage sludge pyrolysis by its pyrochar is improved. • Pyrochar obtained from CaO conditioned sewage sludge was used as reforming catalyst. • The tar cracking and H 2 generation of sludge volatile were significantly promoted. • The CaO conditioning promoted both the Fe-O formation and high dispersion of CaO. [ABSTRACT FROM AUTHOR]

Fast pyrolysis over CaO coupled with fractional condensation was proposed to facilitate the efficient utilization of food waste digestate (FD) and upgrading py-oil. The three-stage fractional condensation temperature was optimized and the effect of CaO catalytic pyrolysis as well as the fractional condensation behavior for enrichment of high value-added nitrogen-containing components (NCCs) were evaluated. The results indicated that fractional condensation temperature was set to 0 °C, 60 °C and 120 °C, which were suitable for enriching NCCs, water and phenols, respectively. In addition, the application of CaO inhibited the production of water during the pyrolysis process of FD and increased the lower heating values of py-oil. Fast pyrolysis over CaO coupled with fractional condensation decreased the content of oxygen-containing compounds (OCCs) and promoted the enrichment of NCCs (71.14 %) in the low-temperature condensation stage, especially the pyrroles (29.03 %). In addition, the formation path of pyrroles and the effect of CaO on the process evolution were proposed. [Display omitted] • Co-pyrolysis behavior of FD and CH with and without CaO catalysts was studied. • Three-stage fractional condensation temperature was optimized to 0 °C, 60 °C, 120 °C. • CaO catalyst promoted the enrichment of NCCs (71.14%) in py-oil-l. • Formation path of pyrroles and the effect of CaO on process evolution were proposed. [ABSTRACT FROM AUTHOR]

• Obvious kinetic compensation effects were found during hydrochar gasification. • Formation of fixed carbon by HTC lowered char-CO 2 gasification reactivity. • HTC treatment had determinant impact on chemical composition of pyrolytic volatiles. • Positive correlation of carbon functionality and volatile aromatics was found. • Mild HTC pretreatment is encouraging in combination with gasification. Hydrothermal carbonization (HTC) combined with subsequent thermochemical conversion is an effective approach for sewage sludge (SS) to energy. In this work, HTC pretreatment of SS was performed. Then the properties of released volatiles and the remaining char-CO 2 gasification after pyrolysis were evaluated via the multiple kinetic model and combined instrumental analyses. The gasification behavior of these samples exhibited slightly different due to high ash content and limited fixed carbon, although the aromatic structure in the hydrochars developed as HTC proceeded. Kinetic analysis indicated that volume reaction model (VRM) with chemical reaction order of 1.5 showed high correlation coefficients (R 2>0.99) for all carbonized samples. There was an obvious kinetic compensation effect in the char gasification step, and activation energy (E) and pre-exponential factor (A) of these samples followed a positive correlation relationship as lnA = 0.1037 × E + 0.3579. The formation of fixed carbon in the hydrochar samples was conserved during pyrolysis, which lowered the average gasification reactivity of char. Py-GC/MS demonstrated that the chemical composition of pyrolytic volatiles was found to be mainly determinant by HTC conditions. The share of aromatics in the volatiles was in a positive correlation with the evolution of carbon functionality in the hydrochar samples. Above in all, HTC temperature exerted a more significant effect on the fuel properties of hydrochar samples than HTC duration did, which also indicated by their subsequent thermochemical conversion. These findings can provide essential knowledge on the thermochemical conversion of hydrochar samples and favor the designing, optimization, and scaling up of the process. [ABSTRACT FROM AUTHOR]