Huaqing Xie

Hydrogen production via steam reforming of bio-oil model compounds over supported nickel catalysts

Abstract The steam reforming of four bio-oil model compounds (acetic acid, ethanol, acetone and phenol) was investigated over Ni-based catalysts supported on Al 2 O 3 modified by Mg, Ce or Co in this paper. The activation process can improve the catalytic activity with the change of high-valence Ni (Ni 2 O 3 , NiO) to low-valence Ni (Ni, NiO). Among these catalysts after activation, the Ce-Ni/Co catalyst showed the best catalytic activity for the steam reforming of all the four model compounds. After long-term experiment at 700 °C and the S/C ratio of 9, the Ce-Ni/Co catalyst still maintained excellent stability for the steam reforming of the simulated bio-oil (mixed by the four compounds with the equal masses). With CaO calcinated from calcium acetate as CO 2 sorbent, the catalytic steam reforming experiment combined with continuous in situ CO 2 adsorption was performed. With the comparison of the case without the adding of CO 2 sorbent, the hydrogen concentration was dramatically improved from 74.8% to 92.3%, with the CO 2 concentration obviously decreased from 19.90% to 1.88%.

Bio-oil production by fast pyrolysis from agriculture residue in northeastern China

In this paper, three typical agriculture residues (corn cob (CC), peanut shell (PS), and pine cone (PC)) from northeastern China were investigated for fast pyrolysis to produce bio-oil. The influences of carrier gas velocity, temperature, and particle size of biomass on bio-oil yield were studied. With the increase of carrier gas velocity, the bio-oil yield increased, but the increase rate of bio-oil yield first increased and then decreased. As temperature increased, the bio-oil yield first increased and then decreased. The variation trends of bio-oil yield with particle size for the three biomasses were different. For CC, the bio-oil yield increased with the reduction of the granularity; but it was completely opposite for PS and PC. The main components of the exhaust gas were CO2, CO, H2, and small quantities of CHx. The compounds of bio-oil were mostly with oxygen functional groups, resulting in the higher content of oxygen element, then leading to low calorific value.

Study on pyrolysis characteristics and kinetics of biomass and its components

With thermogravimetric analyzer, the pyrolysis characteristics of two kinds of biomass (pine cone (PC) and corn cob (CC)) and their main mix components (neutral detergent fiber, acid detergent fiber, and strong acid detergent fiber (SADF)) extracted by Van Soest analysis were studied under three heating rates (10, 20, and 40 K/min). Similar pyrolysis trends were obtained for the two original samples (OSs) and the same mix components, but the differences of the start, end, and reaction rate peak points, the residue ratios, and even the peak numbers of the pyrolysis reaction exist. Besides, to some extent the three components (hemi-cellulose, cellulose, and lignin) have the synergistic effect. On the basis of thermogravimetric analysis, the kinetic analysis of the original samples and the SADF (seen as lignin) was performed. The novel two-step method of model sifting was applied to select the most reasonable mechanism model. Different samples have different models, but the mechanism model of the same sample...

Pyrolysis characteristics and kinetics of lignin derived from three agricultural wastes

With thermogravimetric analyzer, the pyrolysis characteristics of three kinds of lignin from agricultural wastes were studied under three heating rates (10, 20, and 40 K/min). The increase of heating rate could advance the final pyrolysis degree and the pyrolysis reaction rate. In the main pyrolysis region, the lignin samples of corn cob (CC) and peanut shell (PS) showed two peaks of reaction rate curves, yet three peaks for the pine cone (PC) lignin. With the model-free Starink methods, it was found in the previous sections of all the lignin samples, the E values changed widely, and yet in the last sections, the E values were fairly stable. With the model-fitting methods, the kinetic parameters of CC and PS showed a good consistency: both of the lignin pyrolysis processes fitted F1 model for Coats-Redfern method and F1.5 model for Horowitz-Metzger method, and the E values of the two lignin pyrolysis were fairly close; yet, the parameters of the pyrolysis process of the PC lignin obtained were different f...

Thermogravimetric analysis of the biomass pyrolysis with copper slag as heat carrier

Thermo gravimetric analysis experiments were carried out on pyrolysis of three kinds of biomasses by temperature programming method. Employed by thermogravimetric analyzer, the effects of the type of biomass and the ratio of copper slag addition on pyrolysis were studied. Biomass pyrolysis process can be divided into four stages, dehydration, pre-pyrolysis, pyrolysis and carbonization. The experimental yields in this paper were modeled by CH4, C2H6, C3H8, C2H4 and C3H6, considering first-order primary reaction and reactions of alkanes and alkenes. Copper slag is beneficial for biomass pyrolysis. With Coats–Redfern method, nonlinear regression of biomass catalytic pyrolysis showed that reaction mechanism of pyrolysis process confirms well with shrinking core model (A3). The kinetic parameters and equations were also calculated. Copper slag promotes both the primary reactions of biomass pyrolysis and the Cracking reactions of alkanes and alkenes, but it cannot decrease the activation energy effectively.

PERFORMANCE AND APPARENT REDOX KINETIC OF A CU-BASED OXYGEN CARRIER FOR CHEMICAL LOOPING OXYGEN PRODUCTION

The reactivity of Cu-based oxygen carrier prepared by mechanical mixing for producing oxygen was investigated in a thermogravimetric analyzer. The results show that the oxygen carrier has excellent stability during reduction–oxidation cycles. This oxygen carrier showed a maximum oxygen transport capacity of 0.059 g/g during cycle experiments and the time for one cycle is less than 16 min. Phases and surface morphology of oxygen carriers were measured by X-ray diffraction and scanning electron microscope before and after experiments. The phases of reduced oxygen carrier are only Cu2O and TiO2 and of fresh or oxidized samples are only CuO and TiO2. These reveal that the oxygen carrier is stable using the preparation process and under the operation conditions. SEM images show that the fresh and reacted oxygen carrier particles did not appear to disintegrate after 23 cycles.

Syngas production through biomass/CO2 gasification using granulated blast furnace slag as heat carrier

The emerging technology of biomass/CO2 gasification to recover waste heat from granulated blast furnace (BF) slag for solving the energy crisis and relieving the greenhouse effect was proposed. The gasification performances of biomass/CO2 in granulated BF slag under different reaction temperatures and mole ratios of CO2 to fixed carbon in the biomass (CO2/C) were investigated, and the effects of granulated BF slag on the biomass/CO2 gasification reaction were illuminated. The results showed that with higher gas content, gas yield, and lower heating value (LHV) were obtained with higher reaction temperature. When CO2/C was up to 1, the maximum concentrations of CO and H2 were obtained, and the LHV was near maximum value. Granulated BF slag could promote biomass/CO2 gasification reactions to some degree and also could act as a catalyst in the reaction. Under the optimum conditions, a reaction temperature reaching 1000 °C, CO2/C of 1 and using granulated BF slag as a heat carrier, the maximum syngas concentr...

Direct Reduction of Copper Slag Composite Pellets Within Lignite Using Biomass as Binder

The resource utilization of copper slag is an attractive option of iron resource. Thermal energy recovery and direct reduction (TER-DR) system was proposed in this study. By theoretical analysis, the exergy efficiency of this system can reach to 57.3%. To investigate the feasibility of TER-DR system, copper slag composite pellets within lignite were prepared. As a new binder, pine sawdust was added into the pellets. The diameter of pellets was 20 mm in experiments and the compressive strength of them was up to 831 N when the addition ratio of biomass was 29%. The results showed that the overall iron recovery reached to 90% and the separated iron concentrate was up to 93.5% when the temperature is at 1423 K for 90 min with CaO addition ratio of 0.3. The process reduces the secondary environmental pollution of copper slag and will be applied well in the future.

Tar Removal from Hot Coke Oven Gas for H 2 Amplification with in Situ CO 2 Capture

A novel sorption-enhanced steam reforming (SESR) process of hot coke oven gas (HCOG) was proposed for tar removal and H2 amplification, and was studied with the comparison of conventional steam reforming (SCR) process. Both of the processes could remove tar effectively and improve the H2 amount in the COG obviously. For CSR process, after the temperature and the S/HCOG ratio reached 700 ℃ and 2.4 respectively, the H2 amplification factor kept 4.30 around, with its concentration less than 75%. However, for SESR process, the H2 amount and concentration get improved further, with the optimal temperature moving toward low temperature. At 600 ℃ and the S/HCOG ratio of 2.4, the H2 amplification factor and concentration could reach 4.91 and 97.55% respectively when the CaO/C ratio was 2.0. Under the respective optimal reforming conditions of the two processes, the energy consumption of the SESR process was lower than that of CSR process.

Sorption-enhanced reforming of tar: Influence of the preparation method of CO2 absorbent

To remove tar and produce environment-friendly H2, one of the promising routes is the sorption-enhanced steam reforming (SESR) process, in which the CO2 sorbent is a key element. We prepared the CO2 sorbents with Ca12Al14O33 as carrier with various methods. Their characterizations were examined, and the sample prepared by solgel (SG) method showed the strongest CaO and Ca12Al14O33 phases and the most excellent pore structure among all the samples. Then, a thermogravimetric experiment was conducted, and the results showed that the sample prepared by sol-gel (SG) method had the best CO2 adsorption capacity and excellent long-term cyclic stability. Finally, the sorbent was used into the steam reforming experiments of tar. Under the action of the sorbent, the reforming reaction was enhanced in-situ, with the H2 yield and concentration improved obviously, and especially, H2 concentration can reach over 98.85%.