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We reported for the first time the use of bamboo leaf biomass (BLA) as a silica source for the synthesis of aluminosilicate zeolite A (structure code LTA). The BLA with very high silica purity (ca. 99%) was obtained from combustion of acid-treated bamboo leaves, a cheap and abundant agriculture waste. The formation of zeolite A from the BLA precursor was studied by varying the synthesis conditions, i.e. crystallization time, heating temperature and initial gel molar composition. The study revealed that the synthesis parameters had profound effects on crystalline phase, morphology and crystal size of the zeolite A produced. Moreover, this study also demonstrated that the BLA-synthesized zeolite A showed excellent catalytic performance in solvent-free cyanoethylation reaction of methanol under moisture-tolerant and autogenic pressure conditions, with ca. 82% reactant conversion and 100% product selectivity even reused up to ten reaction cycles. [ABSTRACT FROM AUTHOR]

The formation of colloidal AlPO-5 nanocrystals were studied under hydrothermal and microwave conditions in the presence of a new templating agent, 1-ethyl-2,3-dimethylimidazolium hydroxide ([edmim]OH). The syntheses were performed by varying the synthesis conditions, i.e. crystallization time, heating temperature, molar composition and synthesis method. The study revealed that the synthesis parameters had profound effects on crystal growth and physico-chemical properties of AlPO-5 nanocrystals. The resulting AlPO-5 nanocrystals were colloidally stable and the crystallite size with defined shapes can be controlled in the range of 50–900 nm. Moreover, this study demonstrated a facile and fast microwave synthesis method whereby AlPO-5 nanocrystals could be obtained within several minutes instead of hours. The microwave-synthesized AlPO-5 nanocrystals had higher water sorption capacity, higher energy density and fast water desorption than the hydrothermal-synthesized counterpart making it a promising material for water sorption applications. [ABSTRACT FROM AUTHOR]

Synthesis of EMT zeolite nanocrystals from rice husk ash biomass (RHA) under continuous ultrasonic irradiation is reported. The aging, nucleation and crystallization stages of EMT zeolite in the system were monitored at ambient temperature, and compared with the conventional hydrothermal method. It was found that ultrasonic wave induced rapid crystal growth of the nanosized EMT zeolite. Complete crystallization of EMT nanocrystals was achieved within 24 h which was much faster than conventional hydrothermal synthesis (36 h). Furthermore, XRD and TEM analyses revealed that more nuclei were formed during the nucleation stage, allowing the preparation of smaller zeolite nanocrystals with high crystallinity. The results also showed that sonocrystallization produced EMT zeolite with high yield (ca. 80%). The ultrasound-prepared EMT nanocrystals were also found to have high porosity and high hydrophilicity, making the material promising for water sorption applications including vapor sensing, heat pump and adsorption technologies. [ABSTRACT FROM AUTHOR]

A detailed investigation on the crystallization of offretite (OFF) zeolite templated by non-toxic cetyltrimethylammonium bromide (CTABr) is reported. Various hydrothermal synthesis conditions are prepared by systematically adjusting the synthesis variables, namely crystallization time, heating temperature and amount of reactants (SiO 2 , Al 2 O 3 , K 2 O, M 2 O (M = Na+, Cs+), CTABr and H 2 O) to investigate their effects on the crystal growth of OFF zeolite. It is shown that each variable has its profound influences on the crystallization process, which further affect the properties of final zeolite products (e.g. phase purity, morphology, crystal size). Unlike classical synthesis pathway using tetramethylammonium (TMA+) as organic template, the CTABr-templating approach successfully produces large OFF single crystals (framework Si/Al ratio = 4.11) with hexagonal prism shape (ca. 9.4 × 1.8 μm2) and smooth surface. Besides that, the OFF zeolite (81.9% conversion) also shows comparable or even higher catalytic performance than other zeolites reported in this work and other works in microwave assisted-Knoevenagel reaction of benzaldehyde and ethyl cyanoacetate, offering a sustainable and facile pathway for preparing zeolitic materials for advanced applications. [Display omitted] • Offretite (OFF) zeolite is synthesized using CTABr amphiphile-templating method. • Various synthesis conditions are studied. • Large OFF single crystals with hexagonal prism shape are successfully synthesized. • CTABr serves as both structure-directing agent and mesoporogen. • The OFF zeolite shows high activity in microwave assisted-Knoevenagel reaction. [ABSTRACT FROM AUTHOR]

Abstract Alkali metal-containing NKX-2 (M-NKX-2) aluminophosphite crystals were hydrothermally synthesized in the Al 2 O 3 –P 2 O 5 –M 2 O–H 2 O system for the first time using various alkali metal hydroxides (MOH: M = Li, Na, K, Cs). The results showed that NKX-2 crystalline phase could be obtained within several hours without using harmful organic amine structure-directing agent. In addition, the alkali metal hydroxides played an important role in controlling the crystallization rate and the morphology of M-NKX-2 particles in aqueous medium. The resulting M-NKX-2 solids possessed basicity which was catalytically active in base-catalyzed cyanoethylation reaction of methanol. Graphical abstract Image Highlights • Alkali metal containing NKX-2 is synthesized in Al 2 O 3 –P 2 O 5 –Na 2 O–H 2 O system. • The use of different metal hydroxides significantly alters the crystallization time. • The morphological and crystallographic properties are also changed. • The solids exhibit basic character and are active in cyanoethylation of methanol. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate framework-8 (ZIF-8) is a microporous and crystalline material with strong prospect for many engineering applications. In particular, nanosized ZIF-8 particles with well-defined structure and aperture are highly desirable. In this study, nanosized ZIF-8 particles with narrow and monomodal particle size distribution were successfully synthesized by carrying out the ZIF-8 synthesis in ice bath condition using high concentrations of zinc (Zn 2+ , 0.20 M) and 2-methylimidazolate (2-mIm − , 1.60 M) ions. Under low temperature (5 °C), ZIF-8 nucleation was enhanced while the subsequent ZIF-8 nuclei growth was suppressed to produce monomodal particle size with mean particle size of ca. 60 nm. The ZIF-8 nanoparticles were also shown to be fully crystalline and possessed proper chemical structure with well-developed pore network as well as good thermal stability up to 200 °C. [ABSTRACT FROM AUTHOR]

An investigation of nanosized potassium aluminosilicate F-type zeolite (K-F, structure code EDI) converted from rice husk ash (RHA) is reported. The crystallization process was studied in an organic template-free system under microwave radiation at 100 °C and the evolution was followed by spectroscopy and microscopy techniques. The study indicated that the crystallization rate of K-F zeolite was significantly enhanced using microwave radiation. The zeolite started to nucleate at 0.5 min and flattened cuboid shaped K-F zeolite crystals (ca. 39 nm, Si/Al = 1.26) were formed after 2 min onwards. The nanocrystalline K-F zeolite exhibited good catalytic performance in solvent-free Aldol condensation reaction between benzaldehyde and heptanal, with ca. 75% reactant conversion and ca. 67% jasminaldehyde selectivity even after fifth cycle of reaction. [ABSTRACT FROM AUTHOR]

SAPO-35 zeolite (LEV topology) is an 8-membered ring zeolite material that offers high selectivity and activity in separation and catalysis but this microporous material can only be crystallized using hexamethyleneimine, quinuclidine and cyclohexylamine organic templates thus far. Herein, the hydrothermal synthesis and crystallization evolution of SAPO-35 using a novel N -heterocyclic organic template, namely 1-propylpyridinium hydroxide ([PPy]OH), are reported. As compared to the previous reported hexamethyleneimine-templated synthesis conditions (24 h, 200 °C), the current system requires merely 21 h to fully crystallize SAPO-35 using [PPy]OH new template. Furthermore, the current system also witnesses a different route for crystallizing SAPO-35 where dissolution of reactants (induction), nucleation, crystal growth and intrazeolite transformation from SAPO-34 to SAPO-35 are observed. The resulting SAPO-35 zeolite of high porosity and acidity is active and selective in the catalytic conversion of levulinic acid into ethyl levulinate―a biofuel additive―under non-microwave instant heating, where it shows 96.3% conversion and 100% selectivity towards ethyl levulinate after 20 min at 190 °C with high catalyst reusability. Hence, this work offers a promising route to crystallize SAPO-35 that is benign for catalytic biofuel upgrading. [Display omitted] • Crystallization evolution of SAPO-35 using a novel organic template. • Different route for crystallizing SAPO-35 is observed. • The crystallization time using new template is shorter than previous ones. • The SAPO-35 catalyst is active in the production of ethyl levulinate biofuel additive. • 96.3% conversion and 100% ethyl levulinate selectivity are recorded in 20 min at 190 °C. [ABSTRACT FROM AUTHOR]

A detailed study on the formation of nanosized K-MER zeolite from a template-free hydrogel system is reported. By using a new recipe and bamboo leave ash (BLA) as a reactive silica source, the K-MER zeolite crystallization time has been shortened from 15 days to 6 h at 180 °C, enabling the investigation of induction, nucleation and crystal growth of nanoscale K-MER zeolite using spectroscopy and microscopy techniques. The resulting zeolite nanorods ((45.1 ± 14.5 nm length) × (3.9 ± 1.9 nm width)) have a Si/Al ratio of 2.31 and they tend to assemble in parallel forming bulkier bundle-like secondary structure ((728 ± 171 nm length) × (251 ± 49 nm width). The nanocrystals (84.3% conversion and yield, 100% selective to ethyl 2-cyano-3-phenylacrylate (ECP)) show better catalytic performance than other homogeneous base catalysts (92–99% conversion, 82–84% yield) in Knoevenagel reaction of benzaldehyde and ethyl cyanoacetate under non-microwave instant heating condition, thus offering an eco-friendly approach for synthesizing highly selective solid base catalyst for synthesizing pure fine chemicals. Image 1 • Zeolite K-MER nanorods are prepared free of organic template. • Nucleation and crystallization of nanozeolites in template-free hydrogel are studied. • Fully crystalline zeolite nanorods (ca. 45 × 4 nm2, Si/Al = 2.31) form after 6 h. • The nanocrystals are active in Knoevenagel condensation reaction. • High solid yield makes large-scale production of highly basic nanozeolite feasible. [ABSTRACT FROM AUTHOR]

Morphological characteristics of zeolites can have significant effects on the catalytic reactions. However, the roles of zeolite morphology on catalytic reactions, particularly Friedel-Crafts acylation of 2-methylfuran, are still not clear. Hence, LTL-type zeolites with different morphologies are prepared by using bamboo leaf bio-silica source where the zeolites are used to elucidate the morphological properties in this acylation reaction. The results show that LTL zeolites with short-rod, cylindrical, stick-like and nanosized shapes can be prepared by simply tuning the water content of the precursor hydrogels and the crystallization time. The morphological properties of LTL zeolites are also found to have pronounced influences on their surface properties (surface areas, pore volumes, number of micropore channels, textural properties) and acidity (amount, strength and type) where these properties affect their catalytic activity in acylation of 2-methylfuran under non-microwave instant heating condition. Furthermore, the influence of temperature and heating time on the kinetics of catalytic acylation of 2-methylfuran, and the catalytic comparative study between nanosized LTL zeolite and several homogeneous and heterogeneous catalysts are also discussed. Image 1048912 • LTL zeolites with various morphologies are prepared using bamboo leaf ash silica. • The morphological properties influence zeolite surface properties and acidity. • The catalytic behaviour of LTL zeolites is tested in acylation of 2-methylfuran. • Nanosized LTL zeolite has the best performance among the LTL zeolites prepared. • LTL nanozeolite shows better performance than common liquid and solid catalysts. [ABSTRACT FROM AUTHOR]