Co-pyrolysis behavior of microalgae biomass and low-rank coal: Kinetic analysis of the main volatile products.

This work studied the kinetic characteristics of volatile products from co-pyrolysis of microalgae and low-rank coal. Iso-conversional method was applied to calculate the reaction order, activation energy and pre-exponential factor of gaseous products (H2, CO, CH4, and CO2) and benzene. The results indicated the activation energy of H2 generating from both individual and mixing samples was the highest, meaning H2 was the hardest to generate during the pyrolysis process. The values of activation energy from the formation of CO and benzene from low-rank coal and green algae were 31.11, 32.44, 18.21 and 24.31 kJ·mol-1, respectively. The formation of benzene and CO were easier than other volatile products due to the lower activation energy. Synergistic effects were observed from the formation of CO2, the addition of green algae decreased the activation energy. The order of the activation energy was in agreement with that of the releasing sequence of main volatile products.

On-line analysis on the interaction between organic compounds from co-pyrolysis of microalgae and low-rank coal: Thermal behavior and kinetic characteristics.

The interaction between organic compounds from microalgae and low-rank coal during the co-pyrolysis process was explored via thermogravimetric analyzer combined with an online mass spectrometer. The influence of Glycine (GLE) on thermal behavior and kinetic characteristics from gaseous products generation of mixtures of acid washed low-rank coal (ALC) were investigated. Positive and negative synergistic effects from the pyrolysis parameters and products distribution were observed due to the interaction between GLE and ALC. The addition of GLE promoted the char formation under 75 wt% mixing ratio, with about 24 wt% deviation between the calculated value and experimental value. Negative synergistic effects from yield of CO2 and CH4 were found. Kinetic results showed that the order for activation energy was E(H2) > E(CH4) > E(CO) > E(CO2), which was consistent with the releasing sequence.

Co-pyrolysis behavior of microalgae biomass and low-quality coal: Products distributions, char-surface morphology, and synergistic effects.

In this work, the distributions and releasing properties of the primary volatile products during co-pyrolysis of low-rank coal and green algae (GA) has been studied using fixed-bed reactor with online mass spectrometry. Surface morphology of the char was described quantitatively by SEM combined with fractal theory. Different forms of synergistic effects existed from both the yields of products and composition of the main gaseous products. Positive synergistic effects from tar yield were observed under 25% of GA from 600 to 850 °C, indicating GA promoted the formation of tar. Opposite synergistic effects on the content of H2 and CO were gained when the mass ratio of GA was 50%. The fractal dimensions of co-pyrolysis char were less than the calculated values except under 650 °C, which meant the GA promoted the homogeneity of char surface. This work could provide essential data for proper operation parameters selecting for co-pyrolysis.

Thermal characteristics and surface morphology of char during co-pyrolysis of low-rank coal blended with microalgal biomass: Effects of Nannochloropsis and Chlorella.

In this work, the influence of Nannochloropsis and Chlorella on the thermal behavior and surface morphology of char during the co-pyrolysis process were explored. Thermogravimetric and iso-conversional methods were applied to analyzing the pyrolytic and kinetic characteristics for different mass ratios of microalgae and low-rank coal (0, 3:1, 1:1, 1:3 and 1). Fractal theory was used to quantitatively determine the effect of microalgae on the morphological texture of co-pyrolysis char. The result indicated that both the Nannochloropsis and Chlorella promoted the release of volatile from low-rank coal. Different synergistic effects on the thermal parameters and yield of volatile were observed, which could be attributed to the different compositions in the Nannochloropsis and Chlorella and operating condition. The distribution of activation energies shows nonadditive characteristics. Fractal dimensions of the co-pyrolysis char were higher than the individual char, indicating the promotion of disordered degree due to the addition of microalgae.