Oxygen-vacancy-anchoring Ni_(x)O_(y) loading towards efficient hydrogen evolution via photo-thermal coupling reaction

Oxygen vacancy(Vo)is a significant component in defect engineering.The present work reports the anchoring effects of initial Vo for further loading modifications and the reducing capacity of photoinduced Vo for pure water splitting.Herein,we propose Ni-loaded Cu-doped TiO_(2)(NCT)materials by successive doping and loading.The continuously added Ni ions should accumulate around the Vos and gradually grow into complete nickel oxide crystals,achieving a higher average valence state of the Ni species.NiO crystals can be detected on a 0.5%NCT sample,while the structure of Ni_(2)O_(3) has been confirmed with a higher nickel mass ratio.Moreover,the introduction of nickel oxide effectively improves the photochemical and electrochemical performance by the interface charge separation,finally reaching an H2 yield of 30.6 pmol/g-cat on 0.5%NCT for Vo-based photo-thermal coupling reaction,which consists of Vo generation in photo and Vo consumption in thermal environment.In situ infrared spectroscopy further indicated that the presence of high valence state nickel oxide hindered the H2 formation but effectively promoted the conventional oxidizing reaction,with an H2 yield of 20.6 mmol/g-cat in a methanol-water reaction on the 2.0%NCT material.In summary,Vo controls the morphological structure of Ni loading and produces diverse effects for reactions with dissimilar mechanisms,which provides a novel way to design modifications for promoting various chemical reactions.

Research on coal staged conversion poly-generation system based on fluidized bed

A new coal staged conversion poly-generation system combined coal combustion and pyrolysis has been developed for clean and high efficient utilization of coal.Coal is the first pyrolysed in a fluidized pyrolyzer.The pyrolysis gas is then purified and used for chemical product or liquid fuel production.Tar is collected during purification and can be processed to extract high value product and to make liquid fuels by hydro-refining.Semi-coke from the pyrolysis reactor is burned in a circulating fluidized bed(CFB)combustor for heat or power generation.The system can realize coal multiproduct generation and has a great potential to increase coal utilization value.A 1 MW poly-generation system pilot plant and a 12 MW CFB gas,tar,heat and power poly-generation system was erected.The experimental study focused on the two fluidized bed operation and characterization of gas,tar and char yields and compositions.The results showed that the system could operate stable,and produce about 0.12 m^(3)/kg gas with 22 MJ/m^(3)heating value and about 10 wt%tar when using Huainan bituminous coal under pyrolysis temperature between 500 and 600℃.The produced gases were mainly H_(2),CH_(4),CO,CO_(2),C_(2)H_(4),C_(2)H_(6),C_(3)H_(6)and C_(3)H_(8).The CFB combustor can burn semi-coke steadily.The application prospect of the new system was discussed.

Degradation of PCDD/Fs in MSWI fly ash using a microwave-assisted hydrothermal process

In this work,microwave treatment was introduced to a hydrothermal treatment process to degrade PCDD/Fs(Polychlorinated dibenzo-p-dioxins and dibenzofurans)in municipal solid waste incineration(MSWI)fly ash.Three process additives(NaOH,Na2 HPO4,H2 O),temperatures(150℃,185℃,220℃)and reaction times(1 h,2 h,3 h)were investigated to identify their effect on the disposal of fly ash samples through orthogonal experiments.High-resolution gas chromatography–mass spectrometry(HRGC/MS)was applied to determine the PCDD/F concentrations in MSWI fly ash.The experimental results revealed that 83.7%of total PCDD/Fs was degraded.Reaction temperature was the most important factor for the degradation of the total PCDD/Fs.Both direct destruction and chlorination reactions(the chlorination degree of PCDFs increased)took part in the degradation of PCDD/Fs in fly ash,which was a new discovery.Several PCDD/F indexes determined by the concentration of indicative congeners were found to quantitatively characterize the dioxin toxicity of the fly ash.Furthermore,heavy metals in the fly ash sample were solidified using microwave-assisted hydrothermal treatment,which provided an experimental basis for the simultaneous disposal of dioxins and heavy metals.Thus,the microwave-assisted hydrothermal process should be considered for the future disposal of MSWI fly ash.

A steam dried municipal solid waste gasification and melting process

Considering high-moisture municipal solid waste(MSW)of China,a steam dried MSW gasification and melting process was proposed,the feasibility was tested,and the mass and energy balance was analyzed.Preliminary experiments were conducted using a fixed-bed drying apparatus,a 200 kg per day fluidized-bed gasifier,and a swirl melting furnace.Moisture percentage was reduced from 50%to 20%roughly when MSW was dried by slightly superheated steam of 150℃-350℃ within 40 min.When the temperature was less than 250℃,no incondensable gas was produced during the drying process.The gasifier ran at 550℃-700℃with an air equivalence ratio(ER)of 0.2-0.4.The temperature of the swirl melting furnace reached about 1240℃ when the gasification ER was 0.3 and the total ER was 1.1.At these conditions,the fly ash concentration in the flue gas was 1.7 g·(Nm^(3))^(-1),which meant over 95%fly ash was trapped in the furnace and discharged as slag.85%of Ni and Cr were bound in the slag,as well as 60%of Cu.The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97%when MSWis dried by steam of 200℃.The boiler heat efficiency is sensitive to three important parameters,including the temperature of preheated MSW,the moisture percentage of dried MSWand the fly ash percentage in the total ash.

SO2 Emission Characteristics and BP Neural Networks Prediction in MSW/Coal Co-Fired Fluidized Beds

The SO_2 emission characteristics of typical MSW components and their mixtures have been investigated in aΦ150mm fluidized bed.Some influencing factors of SO_2 emission in MSW fluidized bed incinerator were foundout in this study.The SO2 emission is increasing with the growth of the bed temperature,and it is rising with theincreasing oxygen concentration at furnace exit.When the weight percentage of auxiliary coal is being raised,theconversion rate of S to SO_2 is largely going up.The SO_2 emission decreases if the desulfurizing agent (CaCO_3) isadded during the incineration process,but the desulfurizing efficiency is weakened with the enhancement of thebed temperature.The fuel moisture content has a slight effect on the SO_2 emission. Based on these experimentalresults, a 12×6×1 three-layer 13P neural networks prediction model of SOR emission in MSW/coal co-firedfluidized bed incinerator was built.The prediction results of this model give good agreement with theexperimental results,which indicates that the model has relatively high accuracy and good generalization ability.It was found that BP neural network is an effectual method used to predict the SO_2 emission of MSW/coalco-fired fluidized bed incinerator.