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Considering the traditional time-consuming synthesis route and diffusion-limited micropore system of SAPO-11 (i.e., SAPO-11W), a hydroxyl radical assisted method has been developed to prepare hierarchical SAPO-11 within 5 min (i.e., SAPO-11M). Compared to previous reports, the unique contribution is to induce hydroxyl radicals by exposing carbon materials to microwave irradiation in an oxygen-containing atmosphere. Carbon materials play a dual role as mesopore filler and hydroxyl radical initiator. When employed to prepare deoxygenation catalysts for stearic acids, a higher selectivity for C15–C18 and isomers is observed due to the mild acidity of SAPO-11M. The Lewis-rich acidity of SAPO-11M exhibits an electron deficiency to interact with the hydroxyl oxygen atoms and promotes the hydrodeoxygenation of stearic acids with excellent atom economy. These results are important for opening up a new prospect of synthesizing SAPO molecular sieves (e.g., SAPO-11 and SAPO-5) by an efficient and facile route. [ABSTRACT FROM AUTHOR]

• Lignin reacts with alcohols to 3,4-dimethoxyphenyl acetic acid esters over L-MCM-41. • L-MCM-41 has been easily prepared by UV light accelerating. • The L-MCM-41 shows enhanced Lewis acidity and stability. The use of lignin to prepare fine chemicals is a hot research topic. Here, we propose a strategy for esterification of the syringyl group, which is abundant in lignin, to produce 3,4-dimethoxyphenyl acetic acid ester. Lignin reacts with alcohols over acidic pure silica catalyst, L-MCM-41, to generate 3,4-dimethoxyphenyl acetic acid esters. The esterification yield from alkali lignin (Indulin AT) reached more than 60%. Furthermore, L-MCM-41 was easily and quickly prepared using hydroxyl free radicals. The obtained L-MCM-41 exhibited enhanced Lewis acidity and stability compared to silica MCM-41 derived from a traditional hydrothermal system. The enhanced Lewis acidity of the surface silicon atoms of L-MCM-41 can be attributed to the electron-withdrawing effect of abundant geminal hydroxyl groups that they bear. Based on spectroscopic data and the concentration of hydroxyl free radicals, the mechanism underpinning the enhanced acidity and stability of the mesoporous silica molecular sieves is proposed. This work enables production of fine chemicals using lignin as feedstock and provides a reliable and simple method for the synthesis of strongly acidic mesoporous silica molecular sieves. [ABSTRACT FROM AUTHOR]

In this work, Mo-MCM-41, Zr-MCM-41, Sn-MCM-41 and Ti-MCM-41 mesoporous molecular sieves were successfully synthesized via hydrothermal synthesis. An acidic group (SO42−, PTSA etc.) was introduced into the mesoporous molecular sieves to obtain modified mesoporous molecular sieve catalysts. The XRD, N2 absorption–desorption isotherms, FT-IR and Py-IR results reveal that PTSA/ZrO2/Mo-MCM-41 had a mesoporous molecular sieve structure containing a large number of acidic centers. The PTSA/ZrO2/Mo-MCM-41 catalyst illustrated superior catalytic performance for synthesis of rosin methyl ester and the esterification rate was 88.2% under the optimized conditions. At the same time, the PTSA/ZrO2/Mo-MCM-41 catalyst has excellent stability and can be recycled and reused with negligible loss in activity over six cycles. [ABSTRACT FROM AUTHOR]

Aluminophosphate molecular sieves with an AEL-type structure and various framework compositions were prepared via a grinding synthesis method (GSM). The rapid crystal growth rate was due to the enhanced interactions between the templates and aluminum species and abundant low-polymerized phosphorus species. The amount of template and water used was substantially reduced, which has a great economic and environment impact for large-scale synthesis. [ABSTRACT FROM AUTHOR]

La/SAPO-11 was synthesized via one-pot method. Lanthanum ions protect framework from distortion under the severe thermal (600 °C, 4 h) and hydrothermal (800 °C, 4 h) conditions. A higher retention of Brønsted acid sites (45.5%) is obtained after hydrothermal treatment. Lanthanum ions enhance the depolymerization of phosphorus species and interaction with phosphorus and aluminum species. In the coexistence of silicon and lanthanum ions, lanthanum ions could not incorporate into zeolite framework. LaPO 4 preserves framework structure from steam attack. In addition, [La(OH) 2 ] + ions compensate structure tensions and increase the bond strength of Al–O inhibiting the desilication reaction during the thermal treatment. The hydrolyzed species of Si (4Al) and Si (3Al) can be recovered by dehydroxylation. In the cracking reaction of n-dodecane, La/SAPO-11 molecular sieve possessing moderate acid sites enhance isomerization reaction (increasing iso-paraffin by 9.5%) and inhibit cracking. The narrow pore has restriction for di-molecular reactions (e.g., hydrogen transfer reaction). [ABSTRACT FROM AUTHOR]

A facile method to modify pore structure, acidic character, and morphology of SAPO-11 molecular sieve was proposed. Aging treatment (e.g., microwave irradiation or lyophilization) is introduced in the preparation of dry gel. It regulates the kinetics of zeolitic nucleation and growth. X-ray diffraction, scanning electron microscopy, N 2 -adsorption, temperature programmed desorption, laser particle analyzer, and 29 Si MAS NMR were employed to investigate the effects of aging treatments on SAPO-11 products. The experimental results indicate that depolymerization reaction of silicon species is enhanced aged by microwave irradiation with a higher temperature (90 °C). Ratio of SM 3 to SM 2 substituting mode increases producing more strong Brønsted acid sites. Lyophilization technology, as another aging method, was employed to control the morphology of SAPO-11. Nano-sized hierarchical SAPO-11 molecular sieve (200 nm in length) is obtained with an oriented growth. Activity of hydroisomerization catalysts is regulated by aging treatment. Cracking reaction attributes to a high conversion nearly 87 wt% for M90. The hydroisomerization reaction is enhanced for M40 due to a large proportion of moderate acid sites. [ABSTRACT FROM AUTHOR]

To increase the yield of iso-hexane and inhibit cracking of isomers in hydroisomerization of n-hexane, hierarchical SAPO-11 was employed to prepare Pt/SAPO-11 catalysts. Hierarchical SAPO-11 was prepared with fluoride ions via an eco-friendly grinding synthesis method. Fluoride ions incorporate into zeolitic framework to form T-F (T = Al and Si) bonds and inhibit the isomorphous substitution of silicon atoms. It endows SAPO-11 intra- and inter-crystalline mesopores and decreases the amount of acid sites. A low diffusion resistance and decreased acidity of catalysts are unfavorable for a subsequent isomerization and cracking of mono-branched iso-hexane. Compared to microporous SAPO-11, catalysts with hierarchical SAPO-11 have a higher selectivity of iso-hexane at a similar conversion. It is reflected as comparable TOF n-C6 = 21.3 h−1 and TOF iso-C6 = 19.9 h−1. Results above propose a facile and green approach to prepare SAPO-11 molecular sieves. The in-situ regulation method of Pt/SAPO-11 is a reference for other types of SAPO supported catalysts. [Display omitted] • The regulation of Pt/SAPO-11 catalysts is achieved with fluoride ions. •Interaction between fluoride ions and zeolitic atoms is investigated. •Fluoride ions introduce mesopores and decrease the particle size of Pt in hydroisomerization catalysts. [ABSTRACT FROM AUTHOR]

• Hierarchical mordenite with macrospores and mesopores is prepared assisted by nanocrystalline cellulose. • A facile and rapid preparation of mordenite is proposed within 6 h under microwave radiation. • Hierarchical mordenite increases the conversion of α -pinene and yields of camphene and limonene. Mordenite molecular sieves were employed for the isomerization of α -pinene to produce limonene and camphene. To decrease diffusion resistance of α -pinene molecules, nanocrystalline cellulose (NCC) was employed as the mesoporous filler to prepare hierarchical mordenite within 6 h under microwave radiation. NCC crystals present as a rod-like morphology twining around crystals and interact with Al(OH) x O y and Si(OH) x O y species. Stronger interaction with Al(OH) x O y species inhibits the incorporation of aluminum into zeolitic framework. The acidity decreases due to a lower surface Si/Al ratio. Besides creating mesopores and macropores, NCC inhibits the growth or assembly of crystals in the short transverse direction of particles. Compared to mordenite without NCC, conversion increases by ∼50 % and the total yields of camphene and limonene are ∼52 % using mordenite catalysts with NCC. It indicates that macro/mesopores enhance the diffusion of α -pinene in mordenites, increase the accessibility of α -pinene with acid sites. After 5-times cycle tests, the conversion decreases from 63 % to 43 % due to the destruction of zeolitic structure during thermal treatment. In this study, a green synthesis route templated with NCC and green application in isomerization of α -pinene are proposed. These results are important for the synthesis of zeolites using biomass templates rapidly for biomass conversion process. [ABSTRACT FROM AUTHOR]

SAPO-11 was synthesized with fluoride ions via a grinding synthesis method. After introducing fluoride ions, (hydro)thermal stability of SAPO-11 was improved. Zeolitic framework keeps stable up to 1000 °C and distortion is inhibited at 800 °C. When tested in hydrothermal conditions (450 °C, 4 h), the retention rate of relative crystallinity and micropore increase by 28% and 7%. A potential mechanism is proposed to explain the role of fluoride ions to enhance the stability of SAPO-11. At the hydrothermal atmosphere, fluoride species enhance surface hydrophobicity, which inhibits the adsorption of water on SAPO-11. Three types of fluoride ions are confirmed: (i) fluoride ions in the pore channel and on the surface, (ii) fluoride ions interacting with silicon atoms and (iii) aluminum atoms. Fluoride ions interacted with aluminum atoms increase Al-O bond strength. The current research proposes a fluoride-assisted method for stability enhancement of SAPO molecular sieves and is important for expanding application of SAPO molecular sieves in severe (hydro)thermal environment. Image 1 • Hydrothermal stable SAPO-11 with a hierarchical pore structure is prepared with fluoride ions. • Specific fluoride species and location of fluoride species are confirmed. • Fluoride ions strengthen Al-O bond, increase surface hydrophobicity, and enhance the hydrothermal stability of SAPO-11. [ABSTRACT FROM AUTHOR]

A hierarchical SAPO-11 was prepared by a grinding synthesis method (GSM) and added as a promoter to increase the iso-paraffin yield of gasoline in fluid catalytic cracking (FCC) reaction. Compared to the classical hydrothermal method, the GSM leads to the creation of intra-crystalline mesopores with the assistance of a surfactant (Cetyltrimethyl Ammonium Bromide, CTAB). CTAB acts as a structure directing agent and as a hard template during the crystallization of SAPO-11. CTAB micelles formed the intra-crystalline mesopores in SAPO-11 crystals. The intra-crystalline mesoporosity of the SAPO-11 is preserved at 800 °C under steaming, which renders the material as an appropriate component of the FCC catalyst. Besides, the presence of mesopores provides isomerization active sites and accelerates the desorption of iso-paraffin. The mesoporous SAPO-11 showed a higher selectivity for iso-paraffin and the yield of iso-paraffin increased by 2%. Image 1 • A grinding synthesis method (GSM) was employed to prepare hierarchical SAPO-11 molecular sieves. • Intra-crystalline mesopores are stable at 800 °C under steam. • Mesopores are favorable to enhance the isomerization activity of catalysts under FCC conditions. [ABSTRACT FROM AUTHOR]

A grinding synthesis approach is employed to prepare water containing gel. SAPO-11G was successfully prepared by a dry gel conversion method using water containing gel assisted by microwave radiation (120–180 °C, 2 h). Compared to hydrothermal system, approach employed in the present study show green characters such as conservation of energy and time, low cost of organic filler, and reducing wastewater discharge. Deoxygenation of stearic acid shows that Ni/SAPO-11 catalysts have a high selectivity to paraffin and a low yield to cracking products. Ni/SAPO-11G has a comparable activity (conversion> 95%) with Ni/SAPO-11H molecular sieves. Coke deposition in SAPO-11G is lower than that in SAPO-11H due to a lower concentration of extra-framework aluminum species (i.e., Lewis acid sites). These results propose a rapid way to prepare zeolites in an environmental friendly route and are important to produce bio-diesel fractions via a deoxygenation reaction. Image 1 • A grinding synthesis method is employed to prepare water containing precursor. • SAPO-11 is prepared using dry gel conversion heated by microwave. • Ni/SAPO-11 catalysts exhibit a high selectivity to C15-18 paraffin in deoxygenation of stearic acid. [ABSTRACT FROM AUTHOR]

To develop effective catalysts for α -pinene isomerization reaction is important to get high valuable products. A hierarchical mordenite molecular sieve is prepared using alkaline treatment assisted by the microwave radiation. After the alkaline treatment, the relative crystalline decreases by ~20% and mesopores are introduced in the mordenite molecular sieve. Compared to conventional heating method, microwave assisted alkaline treatment exhibits a selective etching of zeolitic silicon atoms. Aluminum atoms adjacent to silicon atoms are extracted to form Al–OH hydroxyl groups. These extracted aluminum atoms are reconnected to zeolitic silicon atoms. Mordenite after microwave assisted alkaline treatment has a good dispersion of mesopores, higher retention of BrØnsted acid sites in 12-membered rings, and lower concentration of Lewis acid sites. The isomerization reaction of α -pinene suggests that alkaline treatment increases the accessibility of acid sites for α -pinene molecules. The hierarchical porosity increases the conversion of α -pinene from 46.1 to 94.7%. The yields for camphene and limonene increase by 17.0 and 5.4%, respectively. Disproportionation of limonene is inhibited when using microwave assisted alkaline treated mordenite due to a low concentration of Lewis acid sites. These results are important to propose a facile post modification method to realize a selective extraction of zeolitic framework atoms. Image 1 • Hierarchical mordenite molecule sieves were prepared by the alkaline treatment via a microwave radiation heating method. • A selective extraction method of zeolitic framework atoms is proposed to regulate the type and location of acid sites. • Disproportionation of limonene is inhibited using Mor-2 with a low BrØnsted and Lewis acid sites ratio. [ABSTRACT FROM AUTHOR]

As for metal/zeolite supported phenol hydrodeoxygenation catalysts, it is important to improve the dispersion of metallic sites and build synergistic relationship between metallic and acid sites. The current research proposes a surface modification strategy by introducing CTAB in the NaOH etching of Beta. CTAB interacts with crystal defects to inhibit excessive crystal destruction. Aluminum atoms are protected from being removed and acid sites are reserved. Generated silicon hydroxyl groups anchor Pt0 particles. Pt0 particles are spatial resisted on the internal surface of catalysts to activate C–O bonds of phenol. Preserved acid sites provide reactive sites for dehydration reaction of cyclohexanol on the external surface of Pt/Beta-H. The high phenol conversion (i.e., 92.26 %) and cyclohexane yield (i.e., 7.18 %) were obtained at 80 °C due to the functional synergistic effect between acid and Pt0 sites. Proposed surface modification strategy proposes references for the structure design and development of efficient phenolics hydrodeoxygenation catalysts. [Display omitted] • CTAB regulates the NaOH etching sites of Beta molecular sieves. • Generated silicon hydroxyl groups anchor fine Pt particles. • Synergistic effect of Pt-acid sites of Pt/Beta catalysts is fabricated due to a hollow spatial distribution. [ABSTRACT FROM AUTHOR]

A simple and facile co-calcination strategy of Beta molecular sieves and cerous nitrate is proposed. Based on the results of XRD, UV–Vis, in-situ FTIR, and 29Si MAS NMR techniques, open-site configurations of Ce(III)O 4 and Ce(IV)O 4 tetrahedrons are observed due to a large ionic radius of Ce3+ and Ce4+ ions. Open-site configurations result in a low ratio of BrØnsted and Lewis acid sites in HBeta-Ce-6. In the isomerization of α- pinene, a higher amount of Lewis acid sites increases the yield for camphene. BrØnsted acids are accessible for α- pinene to form limonene due to a high surface area and low coke deposition. Isomorphous incorporation of Ce3+ occurs and a decreasing selectivity for limonene are observed using regenerated catalysts. These results indicate that co-calcination strategy protects Beta molecular sieves from thermal destruction, endows Beta molecular sieves with a higher relative crystallinity and porosity during calcination. [Display omitted] • A simple and facile co-calcination strategy of Beta molecular sieves and cerous nitrate is proposed. • Incorporation of Ce3+/Ce4+ in defects preserves the relative crystallinity and porosity. • A high yield for limonene and camphene is obtained due to the synergistic effect between Brønsted and Lewis acid sites. [ABSTRACT FROM AUTHOR]

• FCCR is employed as raw materials for the synthesis of mordenite molecular sieve. • Species evolution of RCCR in alkaline fusion activation is investigated. • A rapid synthesis without organic fillers is proposed. Considering the complex elemental and phase compositions, it is a challenge to realize the high value utilization of solid residues in the preparation unit of fluid catalytic cracking catalysts (i.e., FCCR). The current research proposes a disposal approach of FCCR by a direct transformation from FCCR to mordenite molecular sieves. Species evaluation of FCCR in alkaline fusion activation is investigated. Ageing temperature/ duration, crystalline temperature/ duration, amount of water and silica sol are systematically optimized. Obtained mordenite molecular sieves are pure and highly crystallized. When employed as catalysts for the isomerization of α -pinene, as-synthesized mordenite molecular sieves have a comparable performance with commercial ones due to the low diffusion resistance of hierarchical pore structure. These researches are important as a reference for the utilization of FCCR in the field of zeolitic synthesis. [ABSTRACT FROM AUTHOR]

• Carbon-silicon composites obtained from rice hush ash are used as silicon source and mesopore filler for the synthesis of zeolites. • Properties of hierarchical intergrowth SAPO-11/SAPO-31 are regulated by changing the calcination temperature of rice husk. • Deoxygenation routes of stearic acid is controllable regulated by optimizing the acid type and nickel dispersion of catalysts. To improve the low temperature fluidity of bio-diesel, a Ni/SAPO catalyst is prepared using hierarchical silicoaluminophosphate (i.e., SAPO-11/SAPO-31) molecular sieves as supports. A rapid, cost-effective, and eco-friendly approach is proposed using carbon-silicon composites from rice husk ash (RHA). The carbon-silicon composite is obtained via an anaerobic calcination of RHA, which acts as the silicon source and mesopore filler, simultaneously. As-synthesized SAPO-11/SAPO-31 intergrowth molecular sieve has a high mesopore volume due to the mesopore filler function of carbon in RHA. A lower crystallization temperature and shorter duration are achieved with the assistance of microwave irradiation. Ni/SAPO catalysts exhibit a high conversion of stearic acids (concentration, 0.5–5 wt%) to form n-/isoparaffins. These results are important to develop a potential efficient catalyst for the upgrade of bio-oil and the novel synthesis method provides reference to the synthesis of other types of SAPO molecular sieves. [ABSTRACT FROM AUTHOR]

• Partial distribution and size of mesopores in Beta molecular sieves are controllable regulated. • Synergistic mechanism of CTAB and NaOH is fabricated by identifying the role of CTAB molecules in the chemical etching process. • Dispersion of supported metallic sites on Beta molecular sieves are improved due to the uniformly distributed mesopores. A selective alkaline etching strategy is reported to prepare hierarchical Beta molecular sieves with cetyltrimethyl ammonium bromide (CTAB). The homogeneity of mesopores is tuned by surface modification of Beta molecular sieves. CTAB selectively interacts with crystal defects and protects primary etched small mesopores from continuous destruction to form large mesopores. Under the synergistic effect of NaOH solution and CTAB, the acidity retention of Beta molecular sieves is higher due to the removal of Si(OSi) 4 rather than Si(OSi) 3 (OAl) species. When employed as the support of Pt/Beta catalysts, hydroxyl adsorption of phenol on Beta molecular sieves and Pt particles are observed. Dispersion of Pt on the surface of Beta molecular sieves is improved due to the uniform distribution of mesopores. A higher dispersion of Pt attributes to a higher deoxygenation conversion of phenol. The unique contribution of the current research is to propose the role of CTAB in alkaline etching process, realizes the controllable porosity regulation, and alleviates the acidity loss of Beta molecular sieves. These results are important to broaden the application fields of aluminum–silicon molecular sieves especially for large molecules engaged reactions and preparation of supported catalysts with a high metal dispersion. [ABSTRACT FROM AUTHOR]

As a silicon‑aluminum solid waste in the preparation of fluid catalytic cracking (FCC) catalysts, residues (named as FCCR) are directly employed as synthesis raw materials without any pretreatments. An eco-friendly and template-free route is proposed to prepare ZSM-5/mordenite intergrowth molecular sieves using FCCR via a microwave assisted hydrothermal method. ZSM-5/mordenite intergrowth molecular sieves with controllable porosity and acidity are obtained. The proportion of ZSM-5 or mordenite molecular sieves is regulated by optimizing synthesis conditions (e.g., amount of seed, heating temperature/ duration, alkalinity, and SiO 2 /Al 2 O 3). ZSM-5/mordenite intergrowth molecular sieves exhibit catalytic performance in the dehydration reaction of glucose to prepare 5-hydroxymethylfurfural (5-HMF). The in-situ FTIR approach proves a dehydration route "glucose→fructose→5-HMF" under the synergistic effect of BrØnsted and Lewis acid sites. These results are important for the disposal of FCCR and eco-friendly synthesis of molecular sieves. • FCCR is directly used as raw materials for the synthesis of zeolite. • The rapid synthesis is achieved using microwave heating method without organic templates. • The proportion of ZSM-5 or mordenite phases is regulated by optimizing synthesis conditions. • Dehydration paths of glucose are investigated by in-situ FTIR techniques. [ABSTRACT FROM AUTHOR]