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Hydrothermal liquefaction (HTL) is a promising route to convert food waste (FW) to value-added biocrude. Real FW collected from a university campus dining hall and three principal FW components, na...

Co-removal of toluene in NH

Toluene and NOx can be co-removed in NH3-SCR unit. The evaluation of toluene oxidation performance with the participation of SCR reactants is momentous but lacking. Herein, a MnCe/HZSM-5 catalyst was prepared to investigate the effects of NO and NH3 on toluene oxidation. The addition of NO and NH3 increased the toluene conversion from 76.6% to 91.8%, but decreased the CO2 selectivity from 60.5% to 34.1% at 250 °C, indicating that more carbon was transferred into the byproducts. NO and NH3 participated in toluene oxidation by reacting with intermediates, such as aldehydes, carboxylic acids or phenol, to form nitriles or nitrobenzene. Most of nitriles and nitrobenzene were in solid byproducts, which deposited on catalyst surface and deactivated the catalyst. SCR reactants accelerated the decrease of Mn4+, Ce3+, Osur proportions and Lewis acid sites, which were the active constituents for toluene oxidation. As a consequence, a faster deactivation occurred. NO was competitively adsorbed on catalyst with toluene, but promoted toluene oxidation. On the contrary, NH3 enhanced toluene adsorption, but inhibited toluene oxidation. The in-situ DRIFTs results showed that NO and NH3 inhibited the deep oxidation of toluene based on the observation of less water, carboxylate and carbonate.

Carbon materials doped with nitrogen have long been used for SO2 removal from flue gases for the benefits of the environment. The role of water is generally regarded as hydration of SO3 which is formed through the oxidization of SO2. However, the hydration of SO2, especially on the surface of N doped carbon materials, was almost ignored. In this study, the hydration of SO2 was investigated in detail on the pyridinic nitrogen (PyN) doped graphene (GP) surfaces. It is found that, compared to the homogeneous hydration of SO2 assisted with NH3 in gas phase, the heterogeneous hydration is much more thermodynamically and kinetically favourable. Specifically, when a single H2O molecule is involved, the energy barrier for SO2 hydration is as low as 0.15 eV, with 0.59 eV released, indicating the hydration of SO2 can occur at rather low water concentration and temperature. Thermodynamic integration molecular dynamics results show the feasibility of the hydrogenated substrate recovery and the immobilized N acting as a catalytic site for SO2 hydration. Our findings show that the heterogeneous hydration of SO2 should be universal and potentially uncover the puzzling reaction mechanism for SO2 catalytic oxidation at low temperature by N doped carbon materials.

Carbon materials doped with nitrogen have long been used for SO2 removal from flue gases for the benefits of the environment. The role of water is generally regarded as hydration of SO3 which is formed through the oxidization of SO2. However, the hydration of SO2, especially on the surface of N doped carbon materials, was almost ignored. In this study, the hydration of SO2 was investigated in detail on the pyridinic nitrogen (PyN) doped graphene (GP) surfaces. It is found that, compared to the homogeneous hydration of SO2 assisted with NH3 in gas phase, the heterogeneous hydration is much more thermodynamically and kinetically favourable. Specifically, when a single H2O molecule is involved, the energy barrier for SO2 hydration is as low as 0.15 eV, with 0.59 eV released, indicating the hydration of SO2 can occur at rather low water concentration and temperature. Thermodynamic integration molecular dynamics results show the feasibility of the hydrogenated substrate recovery and the immobilized N acting as a catalytic site for SO2 hydration. Our findings show that the heterogeneous hydration of SO2 should be universal and potentially uncover the puzzling reaction mechanism for SO2 catalytic oxidation at low temperature by N doped carbon materials.

Carbon materials doped with nitrogen have long been used for SO2 removal from flue gases for the benefits of the environment. The role of water is generally regarded as hydration of SO3 which is formed through the oxidization of SO2. However, the hydration of SO2, especially on the surface of N doped carbon materials, was almost ignored. In this study, the hydration of SO2 was investigated in detail on the pyridinic nitrogen (PyN) doped graphene (GP) surfaces. It is found that, compared to the homogeneous hydration of SO2 assisted with NH3 in gas phase, the heterogeneous hydration is much more thermodynamically and kinetically favourable. Specifically, when a single H2O molecule is involved, the energy barrier for SO2 hydration is as low as 0.15 eV, with 0.59 eV released, indicating the hydration of SO2 can occur at rather low water concentration and temperature. Thermodynamic integration molecular dynamics results show the feasibility of the hydrogenated substrate recovery and the immobilized N acting as a catalytic site for SO2 hydration. Our findings show that the heterogeneous hydration of SO2 should be universal and potentially uncover the puzzling reaction mechanism for SO2 catalytic oxidation at low temperature by N doped carbon materials.

Carbon materials doped with nitrogen have long been used for SO2 removal from flue gases for the benefits of the environment. The role of water is generally regarded as hydration of SO3 which is formed through the oxidization of SO2. However, the hydration of SO2, especially on the surface of N doped carbon materials, was almost ignored. In this study, the hydration of SO2 was investigated in detail on the pyridinic nitrogen (PyN) doped graphene (GP) surfaces. It is found that, compared to the homogeneous hydration of SO2 assisted with NH3 in gas phase, the heterogeneous hydration is much more thermodynamically and kinetically favourable. Specifically, when a single H2O molecule is involved, the energy barrier for SO2 hydration is as low as 0.15 eV, with 0.59 eV released, indicating the hydration of SO2 can occur at rather low water concentration and temperature. Thermodynamic integration molecular dynamics results show the feasibility of the hydrogenated substrate recovery and the immobilized N acting as a catalytic site for SO2 hydration. Our findings show that the heterogeneous hydration of SO2 should be universal and potentially uncover the puzzling reaction mechanism for SO2 catalytic oxidation at low temperature by N doped carbon materials.

Co-removal of toluene in NH3-SCR unit over Mn based catalysts is desirable but still faces the big challenge of byproduct greenhouse gas N2O. In this work, the impacts of toluene on N2O formation mechanism was studied. The main N2O formation pathways in NH3-SCR over Mn-Fe spinel were NH3 oxidation and non-catalytic selective reduction (NSCR), in which NSCR dominated below 250 °C. The N2O from NSCR through both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms was confirmed. And the E-R mechanism was dominant at 200 °C. Toluene was effectively co-removed with NOx with the advantage of N2O inhibition. Toluene suppressed N2O generation from both NH3 oxidation and NSCR. NH3 oxidation by gaseous O2 and catalyst surface oxygen was all limited by toluene, resulting in less adsorbed NH that was further proved by the larger energy barriers of NH3*→NH2* and NH2*→NH* on toluene pre-adsorbed catalyst surface. NO oxidation was also limited, suppressing the generation of adsorbed NO3−. Due to the inhibition of NH3 and NO activation to key intermediates NH and NO3−, respectively, the N2O generation from E-R route was slightly decreased in the presence of toluene, while that from L-H route was completely prohibited at 200 °C.

The influences of four heating rates on the combustion and pyrolysis behavior in the N2 and air atmosphere were investigated by the Fourier transform infrared spectrometry (FTIR) and thermogravimetric (TG) analysis. the distributed activation energy model (DEAM) and Flynn-Wall-Ozawa (FWO) were used to estimate Ea and A, &Delta, H, &Delta, G and &Delta, S. Experimental results showed that the similar thermal behavior emerged, but the temperatures in the air and N2 atmospheres representing the end of the reaction were about 500 &deg, C and 550 &deg, C, respectively. The results of FTIR showed the peak positions were basically the same, but the concentrations of aromatics, aldehydes and ketones produced by pyrolysis in the N2 atmosphere were higher. When the heating rate was 20 K/min, the comprehensive combustion parameters were 56.442 and 6.871 &times, 10&minus, 7%2/(min2&bull, K3) in the air and N2 atmospheres, respectively, indicating that the peanut shells had great potential to become bioenergy.