Eco-friendly synthesis of high silica zeolite Y with choline as green and innocent structure-directing agent

Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.

Cooperative structure-directing effect of choline cation and *BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolite

In this contribution,we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate*BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time.*BEA zeolites,at variance with any other aluminosilicate zeolites,can serve as heterogeneous seeds for the growth of IWR zeolites and play a cooperative structure-directing role.The crystallization process was investigated using multiple techniques to characterize a series of solid products obtained with various crystallization times.The experiments clearly showed the dissolution of the*BEA zeolite and of an intermediate CDO-type structure.A plausible mechanism for the novel cooperative synthesis has been proposed.The crystallization of the IWR zeolite involves several steps,among which the crucial one is believed to be the reassembly of the building units produced from the decomposition of*BEA zeolite seeds,induced by choline molecules.Having similar structure and common building units(four-,five-,and six-membered rings)with the IWR zeolite,the*BEA zeolite is capable of promoting the reassembly of the building units and can thus play a cooperative structure-directing role.By highlighting the cooperative structure-directing effect of organic molecules and heterogeneous seeds,this study opens up new perspectives for the synthesis of target zeolites that are difficult to prepare by traditional methods.This new synthetic route is also expected to shed light on the discovery of novel zeolites.

SYNERGISTIC ACTIVATION OF CHELATING AGENT ON XANTHATE DURING THE FLOTATION OF REFRACTORY COPPER OXIDIZED ORES

For realizing the effective flotation of refractory copper ox-idized ores and developing the activation-flotation theory , the influences of nine different organic chelating agents on xanthate collection pcnver and its adsorption characteristics ivere studied in the flotation of malachite and chrysocolla representatively selected by means of XPS,IR, absorbed quanti-ty measurements and flotation tests.For easily-dissolved malachite flotation , a small amount of chelating agent can obviously enhance xanthate collecting power and make malachite floated easily , and so reduces the consumption of xanthate. For hard-dis-晄olved chrysocolla, chelating agent is able to increase its recovery to 90% , but the chelating agent consumption is high. Chelating agent and xanthate can produce synergistic adsorptions, which follmv Freundlich's adsorption equation on malachite and Chrysocolla surfaces. The high chemical activity of chelating agent and its synergistic activation on xanthate are the key to improving xanthate collection poiver. The synergistic activation of chelat-ing agent on xanthate on melachite surfaces is clearly stronger than on chrysocolla surfaces. According to experimental results, it can be thought that the synergistic activation results from the synergistic complexation of chelating agent and xanthate with copper ions to form biligand-tribasic co-ordination complex.

Molecular simulations of host-guest interactions between zeolite framework STW and its organic structure-directing agents

Zeolites have been widely applied in many chemical processes owing to their featured microporous framework structures.Organic structure-directing agents(OSDAs) play an important role during of the formation of zeolite frameworks via non-bonding host-guest interactions.Understanding these interactions is crucial to the design of OSDAs and the synthesis of target zeolites.Here,we report a molecular simulation study in the host-guest interactions between zeolite framework STW and 21 alkylated imidazolium and pyrazolium cations that have been used as the OSDAs for the synthesis of STW-type zeolites.We find that OSDAs that have successfully directed the formation of STW exhibit stronger host-guest interactions than unsuccessful ones.Furthermore,we find all successful OSDAs possess relatively more negative atomic charges on nitrogen atoms and smaller dipole moments.According to this finding,we have designed seven new alkylated imidazolium and pyrazolium cations that may be suitable for zeolite STW,and verified their structure-directing capability by molecular simulation calculations.

Organic-free,Ultrafast Synthesis of K-CHA Nano-aggregates with Various Morphologies and Their Adsorption Performances

K-Chabazite(K-CHA)zeolites were synthesized with an ultrafast procedure through an eco-friendly and cost-effective“one-pot”method.By solely employing colloidal silica and aluminum hydroxide in the K^(+)/Sr^(2+)system without the assistance of seeds,fluorides or organic structure as directing agents,the K-CHA nano-aggregates were successfully synthesized in a few hours.The crystallization behavior of the gels with different SiO_(2)/Al_(2)O_(3) molar ratios(SARs)was investigated using X-ray diffraction(XRD);scanning electron microscope(SEM);X-ray fluorescence(XRF);27Al and 29Si magic angle spinning nuclear magnetic resonance(MAS NMR);Fourier-transform infrared spectra(FTIR);UV-Raman characterizations.As the nucleation rates were changed with the SARs,three kinds of K-CHA nano-aggregates,namely,hamburger-,disk-and walnut-shaped,were obtained.A possible formation mechanism of the K-CHA nano-aggregates was proposed.Additionally,the walnut-shaped sample with an SAR of 7 possessed the largest pore volume and specific surface area,resulting in the highest methane adsorption capacity.Furthermore,it exhibited a CH_(4)/N_(2) selectivity of more than 3 under relative pressures ranging from 0 to 0.6.This work offers guidance for modifying the stacking modes of other nano-sized zeolites.

An endoplasmic reticulum-targeted organic photothermal agent for enhanced cancer therapy

Developing selectively targeted photothermal agents to reduce side effects in photothermal therapy remains a great challenge. Inspired by the key role of endoplasmic reticulum in the protein synthesis and intracellular signal transduction, particularly for the immunogenic cell death induced by endoplasmic reticulum stress, we developed an endoplasmic reticulum-targeted organic photothermal agent(Ts-PTRGD) for enhancing photothermal therapy of tumor. The photothermal agent was covalently attached with 4-methylbenzenesulfonamide and cyclic Arg-Gly-Asp(c RGD) peptide for realizing the targeting of endoplasmic reticulum and tumor cell. Owing to its amphiphilic properties, it readily self-assembles in water to form nanoparticles. The photothermal agent possesses excellent photophysical properties and biological compatibility. In vitro and in vivo experiments demonstrate that it can actively target endoplasmic reticulum and effectively ablate tumor with near-infrared laser.