• Energy Research

Abstract A facile and low-cost method was developed to synthesize a series of novel heterogeneous catalysts from cyclodextrins and Mg or Zn of salts. These catalysts were demonstrated to be efficient for converting sustainable plant oils to biodiesel under mild conditions (ambient pressure, 65 °C). Mechanistic studies indicated that the excellent performance of the catalysts could be attributed to their unique structural characteristics, wherein both the metal ions and the cyclodextrin units worked cooperatively for synergistic activations of substrates.

Abstract A facile and low-cost method was developed to synthesize a series of novel heterogeneous catalysts from cyclodextrins and Mg or Zn of salts. These catalysts were demonstrated to be efficient for converting sustainable plant oils to biodiesel under mild conditions (ambient pressure, 65 °C). Mechanistic studies indicated that the excellent performance of the catalysts could be attributed to their unique structural characteristics, wherein both the metal ions and the cyclodextrin units worked cooperatively for synergistic activations of substrates.

Due to the source and load prediction errors and uncertainties, the real operation state of microgrid may deviate significantly from the expected state, which leads to prevent the system from reaching its expected economic effects. In order to obtain the optimal economic effects for microgrid scheduling, an optimal microgrid scheduling model considered the demand responses is built in this paper firstly, and then a multi-time scale economic scheduling method based on day-ahead robust optimization and intraday model predictive control (MPC), is developed as well. Moreover, in the day-ahead stage, the long-time scale interval is set as 1 h and the robust optimization is used to address the low-frequency components in prediction errors and uncertainties. Meanwhile, the robust optimization enables to gain the day-head optimal economic scheduling plan for the microgrid and to keep the system operating effectively even when large-scale fluctuations happen. Furthermore, in the intraday stage, the short-time scale interval is set as 15 mins and MPC is adopted to track and correct the day-ahead economic scheduling plan, which enables to address the high-frequency components in prediction errors and uncertainties. Finally, simulation results demonstrate the feasibility of the proposed optimal microgrid scheduling model and the validity of the proposed multi-time scale economic scheduling method.

Due to the source and load prediction errors and uncertainties, the real operation state of microgrid may deviate significantly from the expected state, which leads to prevent the system from reaching its expected economic effects. In order to obtain the optimal economic effects for microgrid scheduling, an optimal microgrid scheduling model considered the demand responses is built in this paper firstly, and then a multi-time scale economic scheduling method based on day-ahead robust optimization and intraday model predictive control (MPC), is developed as well. Moreover, in the day-ahead stage, the long-time scale interval is set as 1 h and the robust optimization is used to address the low-frequency components in prediction errors and uncertainties. Meanwhile, the robust optimization enables to gain the day-head optimal economic scheduling plan for the microgrid and to keep the system operating effectively even when large-scale fluctuations happen. Furthermore, in the intraday stage, the short-time scale interval is set as 15 mins and MPC is adopted to track and correct the day-ahead economic scheduling plan, which enables to address the high-frequency components in prediction errors and uncertainties. Finally, simulation results demonstrate the feasibility of the proposed optimal microgrid scheduling model and the validity of the proposed multi-time scale economic scheduling method.

Abstract Combination of multiple excellent characteristics, such as large surface area, strong acidity, high acid density and good dispersion of active sites, in a mesoporous solid acid catalyst is desirable for achieving superior catalytic activity in production of biodiesel but challenging. Herein, an acidic ionic liquid (IL)-functionalized mesoporous melamine-formaldehyde polymer (MMFP-IL) was prepared for the first time by quaternary ammonization of mesoporous nitrogen-rich melamine-formaldehyde polymer (MMFP) with 1,3-propanesultone, followed by treatment with H3PW12O40 (HPW). The MMFP, containing abundant aminal groups and triazine rings, could be facilely synthesized from lost-cost and readily available monomers (i.e., melamine and paraformaldehyde), which provides massive sites for immobilizing more IL and HPW via chemical post-modification method. The MMFP-IL catalyst was systematically characterized, which was revealed to possess unique and outstanding properties, including abundant mesoporous structures with high specific surface area (283.0 m2/g), high acid concentration (2.2 mmol/g), strong acidity and fine distribution of acid sites. These properties endowed MMFP-IL to have excellent activity in esterification of oleic acid with methanol to produce biodiesel under mild conditions, outperforming those of various solid acids (e.g., commercial strong acidic resins and HPW). In addition, the kinetics and thermodynamics of the reaction were investigated over the MMFP-IL catalyst. More importantly, the MMFP-IL catalyst was robust, heterogeneous, and recyclable without significant deactivation after four cycles, which is attributed to the immobilization of acidic ionic liquid onto the robust MMFP via strong covalent bond.

Abstract Combination of multiple excellent characteristics, such as large surface area, strong acidity, high acid density and good dispersion of active sites, in a mesoporous solid acid catalyst is desirable for achieving superior catalytic activity in production of biodiesel but challenging. Herein, an acidic ionic liquid (IL)-functionalized mesoporous melamine-formaldehyde polymer (MMFP-IL) was prepared for the first time by quaternary ammonization of mesoporous nitrogen-rich melamine-formaldehyde polymer (MMFP) with 1,3-propanesultone, followed by treatment with H3PW12O40 (HPW). The MMFP, containing abundant aminal groups and triazine rings, could be facilely synthesized from lost-cost and readily available monomers (i.e., melamine and paraformaldehyde), which provides massive sites for immobilizing more IL and HPW via chemical post-modification method. The MMFP-IL catalyst was systematically characterized, which was revealed to possess unique and outstanding properties, including abundant mesoporous structures with high specific surface area (283.0 m2/g), high acid concentration (2.2 mmol/g), strong acidity and fine distribution of acid sites. These properties endowed MMFP-IL to have excellent activity in esterification of oleic acid with methanol to produce biodiesel under mild conditions, outperforming those of various solid acids (e.g., commercial strong acidic resins and HPW). In addition, the kinetics and thermodynamics of the reaction were investigated over the MMFP-IL catalyst. More importantly, the MMFP-IL catalyst was robust, heterogeneous, and recyclable without significant deactivation after four cycles, which is attributed to the immobilization of acidic ionic liquid onto the robust MMFP via strong covalent bond.

With the great adjustment of world industrialization and the continuous improvement of energy consumption requirements, the selective conversion of biomass-based platform molecules to high-value chemicals and biofuels has become one of the most important topics of current research. Catalysis is an essential approach to achieve energy-chemical conversion through the “bond breaking-bond formation” principle, which opens a broad world for the energy sector. Single-atom catalysts (SACs) are a new frontier in the field of catalysis in recent years, and exciting achievements have been made in biomass energy chemistry. This mini-review focuses on catalytic conversion of biomass-based levulinic acid (LA) to γ-valerolactone (GVL) over SACs. The current challenges and future development directions of SACs-mediated catalytic upgrading of biomass-based LA to produce value-added GVL, and the preparation and characterization of SACs are analyzed and summarized, aiming to provide theoretical guidance for further development of this emerging field.

With the great adjustment of world industrialization and the continuous improvement of energy consumption requirements, the selective conversion of biomass-based platform molecules to high-value chemicals and biofuels has become one of the most important topics of current research. Catalysis is an essential approach to achieve energy-chemical conversion through the “bond breaking-bond formation” principle, which opens a broad world for the energy sector. Single-atom catalysts (SACs) are a new frontier in the field of catalysis in recent years, and exciting achievements have been made in biomass energy chemistry. This mini-review focuses on catalytic conversion of biomass-based levulinic acid (LA) to γ-valerolactone (GVL) over SACs. The current challenges and future development directions of SACs-mediated catalytic upgrading of biomass-based LA to produce value-added GVL, and the preparation and characterization of SACs are analyzed and summarized, aiming to provide theoretical guidance for further development of this emerging field.