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Hollow mesoporous carbon submicrospheres (HMCNs) have been successfully synthesized via a facile silica-assisted sol–gel strategy, which were further treated with KOH or/and HNO3 to obtain four adsorbents with different structures and surface properties for the removal of dibenzothiophene (DBT). KOH activation can effectively adjust the micro/mesoporous structure by increasing the number of micropores, and HNO3 oxidation can modify the surface properties by introducing oxygen-containing functional groups. HMCNs treated with KOH first and then HNO3 are the best for DBT removal with the adsorption capacity of 33.20 mg S·g–1, which is nearly 45% higher than that of activated carbon with the same treatment. Notably, the adsorption equilibrium can be achieved within only 5 min, much faster than active carbon owing to the existence of abundant mesopores favorable to the diffusion of DBT. The negative ΔG° from thermodynamics result suggests it is a favorable and spontaneous adsorption process.

Slurry-phase hydrocracking (SPHC) of unconventional heavy feedstocks is considered as a promising process to fill the gap between the ever-increasing demand for vehicle fuels and the fast-depleting supply of conventional crude oil. The one-through nature of SPHC processes requires low-cost yet high-performance catalyst. This article reports a simple but effective hydrothermal modification strategy to treat a cheap natural bauxite mineral as a support (HMB) to prepare SPHC catalyst (HMBC) with outstanding catalytic performance. For comparison, an acid-modified bauxite (AMB) derived catalyst (AMBC) was also prepared. The physicochemical properties of HMB, HMBC, AMB and AMBC were systematically characterized, and the catalytic performance of HMBC and AMBC was assessed in the SPHC of a high temperature coal tar (HTCT). The results showed that HMBC exhibited HTCT hydrocracking activity superior to AMBC, attributed to the more suitable acidity of the support HMB and the weaker interaction between MoO 3 and HMB that results in the higher sulfidation degree of molybdenum oxide species and thereby provides more active MoS 2 phases for hydrocracking. Furthermore, compared with the acid treatment previously reported, the hydrothermal modification is simpler, more energy-saving, and more environment-friendly and therefore is feasible for industrial application.

The hydrothermal synthesis of zeolite from chemical Al/Si source in the presence of structure directing agent is considered to be a resource extensive, energy consuming, and environmental unfriendly process. Herein, we report a novel, cost-effective, and eco-friendly synthesis for the preparation of ZSM-5 zeolite from silicon-rich diatomite and aluminum-rich rectorite minerals in the absence of organic structure-directing agent and chemical Al/Si source. Synthesis factors (SiO2/Al2O3, Na2O/SiO2, and H2O/SiO2 molar ratios along with seed content) and crystallization behavior were systematically investigated, providing fundamental knowledges on the formation of ZSM-5 from natural minerals. Synthesis under the optimized conditions (SiO2/Al2O3 ratio of around 38, Na2O/SiO2 ratios of 0.12–0.15, H2O/SiO2 ratios of 15–25, and seed content above 0.5%) led to production of highly crystalline ZSM-5 zeolite with hexagonal prism morphology and large surface area. Various characterization techniques tracking the products at different crystallization times revealed that the crystallization process consisted of three stages: short induction stage (0–6 h), rapid growth stage (6–18 h), and stable growth stage (18–36 h). Moreover, the synthesized ZSM-5 crystals can be used as effective seed for producing the next generation of ZSM-5 zeolite.

Organic templates play a crucial role in zeolite synthesis, but their use causes serious pollutant emissions and increases product costs. Herein, we report a template-free approach to synthesize both microporous and hierarchical ZSM-5 zeolites from natural aluminosilicate mineral, which is achieved by (1) utilizing the mother liquid to construct mesopores without using any mesoscale template and (2) reusing the Si-rich alkali liquor and ion-exchanging solution to improve the atom economy without any alkali/acid liquor discharges. The results show that the resultant zeolites own more open pore channels and less strong acid sites compared with a conventional ZSM-5 zeolite and demonstrate superior catalytic activity in n-octene hydroisomerization. Significantly, compared with the traditional synthesis process, our approach can greatly reduce the material and energy consumptions and pollutant discharges while significantly increase the raw material utilization efficiency, endowing itself as an economic, eco-s...

Selective separation and recovery of Co(II)/Mn(II) from purified terephthalic acid (PTA) production wastewater is very important to reduce the Co(II)/Mn(II) catalysts consumption and control the pollutant discharge. This work employed zeolites NaA, NaX, and HZSM-5 with different pore sizes and Na(I) contents to selectively separate and recover Co(II)/Mn(II) from PTA wastewater and to understand the adsorption mechanism. It is found that only NaA can exclusively adsorb Co(II)/Mn(II) through ion-exchange without adsorbing any aromatic organic compound (AOC); oppositely, HZSM-5 shows the highest adsorption capacity for AOCs but almost no adsorption for Co(II)/Mn(II); and NaX exhibits moderate adsorption capacities for both Co(II)/Mn(II) and AOCs. Moreover, pH can significantly impact the adsorption of both Co(II)/Mn(II) and AOCs due to the competitive adsorption between H(I) and Co(II)/Mn(II) and the electrostatic repulsion between AOCs and zeolites. The adsorption kinetics, isotherms, and thermodynamics were also investigated to lay a good basis for process development. Importantly, bench-scale experiments for simulating the industrial operation were carried out, and the results show that the adsorption capacity of the NaA particles for Co(II)/Mn(II) from the industrial PTA wastewater is 9.1/8.6 mg/g, respectively, without adsorbing any AOC. Therefore, an efficient strategy to selectively separate and recover Co(II)/Mn(II) from PTA wastewater was successfully developed.

The use of natural aluminosilicate minerals as the low-cost starting materials for zeolite synthesis is a field of current interest. However, impurities existing in these minerals greatly affect the purity of final products. Herein, we describe a cheap and green route for synthesizing pure-phase zeolite beta from natural aluminosilicate minerals via a modified nanoscale depolymerization-reorganization approach. The physicochemical and catalytic properties of the synthesized zeolite beta were systematically characterized and assessed, respectively. The results indicate that the resulting zeolite beta possesses more moderate Bronsted acid sites compared with the reference one, and thus exhibits higher catalytic activity in the esterification of acetic acid with ethanol. This methodology demonstrates great perspective for the low-cost and environmentally-benign synthesis of zeolite beta that avoids the use of aluminum- and silicon-containing inorganic chemicals, eliminates the interference of impurities, and reduces the usage of the organic template.

Heterobimetallic zeolites have been considered as highly efficient catalysts to reduce nitrogen oxide emissions, but economic and sustainable preparation methods have been lacking. This paper presents an economic and sustainable one-pot synthesis strategy to prepare the heterobimetallic FeCu-SSZ-13 zeolite (FeCu-SSZ-13M) with high crystallinity via the mesoscale depolymerization-reorganization of natural aluminosilicate minerals without the use of any synthetic silicon-, aluminum-, and iron-containing chemicals. Systematic characterization results reveal that the resultant FeCu-SSZ-13M sample has smaller crystallize size, larger specific surface area and pore volume (especially external specific surface area and mesopore volume), lower acid strength and more isolated Cu2+ and framework Fe3+ ions when compared with Cu-SSZ-13C and FeCu-SSZ-13C prepared from conventional precursors. Therefore, it exhibits outstanding catalytic performance (such as super-wide reaction temperature window, excellent hydrothermal stability, high H2O and SO2 tolerance, and good gaseous hourly space velocity flexibility) in the selective catalytic reduction of NO by NH3. Our research contributes to the design and synthesis of an efficient environmental protection catalyst in an economic and sustainable manner.

A template free synthesis route was developed for the synthesis of hierarchical zeolite Beta from a natural layered aluminosilicate mineral kaolin. Detailed study on the crystallization of zeolite Beta established the optimized synthesis condition, and the synthesized hierarchical Beta zeolite was fully studied by XRD, IR, SEM, TEM, BET, NH3-TPD, Py-IR and NMR techniques. The characterization results reveal that the hierarchical Beta zeolite possesses good crystallinity, bimodal pore architecture, large surface area, big pore volume, high acid site concentration and excellent hydrothermal stability. An improved catalytic performance was achieved in hierarchical Beta zeolite for the esterification of acetic acid with benzyl alcohol, and the high activity and selectivity in this zeolite are mainly attributed to the presence of mesopores for accelerating the intraparticle diffusion rate of both reactant and product. This novel synthesis methodology provides a low-cost and environmentally-benign way for the preparation of hierarchical Beta zeolite, which could serve a sustainable platform of large-scale production of hierarchical zeolite for practical application.