ZSM-5 Molecular Sieve Research Articles

Nano-lamellar H-ZSM-5 molecular sieves for enhanced indoor air purification: Synthesis and adsorption characterization.

The rapid growth of cities has been accompanied by problems with urban air quality, making air pollution challenging to manage. In this situation, people focus on indoor building materials to improve air quality. In this paper, a novel bola-type surfactant was synthesized and used as a template, using ethyl orthosilicate and sodium meta-aluminate as the silicon and aluminum source, in the ratio of n(NaOH): n(NaAIO2): n(SiO2): n(SDA): n(H2O) as 30:2.5:120:5:4800. Hydrothermal preparation of ZSM-5 molecular sieves with a nanosheet structure (H-ZSM-5) was accomplished. The manufactured lamellar ZSM-5 molecular sieves were examined using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and adsorption and desorption techniques. Traditional microporous ZSM-5 had a considerably lower static adsorption of formaldehyde molecules. The findings demonstrated that the nano-lamellar H-ZSM-5 molecular sieve can purify and eliminate larger molecular VOCs inside because it has the ability to adsorb larger molecular diameter VOCs. Additionally, the effectiveness of the adsorption was assessed using toluene vapour molecules with higher molecular diameters. The findings demonstrate that the nanosheet H-ZSM-5 molecular sieve can remove bigger molecule VOCs from indoor air and can be utilised to purify indoor spaces. This study offers a fresh approach to indoor environmental cleanup by demonstrating the capability of nano-lamellar H-ZSM-5 molecular sieves for molecular adsorption.

Self-assembled chromium-based nitrogen carrier for chemical looping ammonia synthesis

Industrially, ammonia is generated mainly using the energy-intensive and CO2-emitting Haber-Bosch process, which is not conducive to sustainable economic and social development. The chemical looping ammonia synthesis (CLAS) is capable of coupling green energy, which is one of the available alternatives to the Haber-Bosch process, but the ammonia production rate of most of its nitrogen carriers is unsatisfactory. In this work, we designed a self-assembled nitrogen carrier using ZSM-5 molecular sieve (ZSM-5) and nickel (Ni) to modify chromium nitride (CrN). ZSM-5 molecular sieves have a rich pore structure, which enables the gas-phase reactants to react with the lattice nitrogen in the subsurface layer of the nitrogen carrier. Nickel can facilitate the dissociation of hydrogen during hydrogenation due to its higher hydrogen affinity. The ammonia production rate of the nitrogen carrier can reach 451.2 μmol g−1 h−1 at 700 °C and atmospheric pressure, and be able to remain 358 μmol g−1 h−1 after eight cycles. Furthermore, we also propose a full-coverage design strategy for nitrogen carriers: simultaneous optimization of the chemical and mass transfer processes in the nitrogen carrier. This work advances the design of high-performance nitrogen carrier, thus facilitating the applications of CLAS for the distributed ammonia synthesis.

SiO with ZSM-5 to regulate interfacial stability for fast-charging lithium-ion batteries

Silicon monoxide (SiO) anodes hold great promise for the high-energy advanced battery systems. However, their rate and cycling behavior confront rapid capacity degradation due to the sluggish charge transfer kinetic and serious volume expansion. Though different tactics mitigate this degradation, the effective strategy is still needed to further improve the charge diffusion and mass shift. Here, it is suggested that the stable and fast ion transfer channels are established and dominated by the ZSM-5, combining with PEO, which depresses the volume expansion and leads to the enhanced tolerance during cycling for the SiO anodes. The different molar ratio of ZSM-5/PEO solid state electrolyte impacts greatly the battery performance. This study conducts the interface issues and proposes the integration of ZSM-5 molecular sieve to improve the contact between the solid electrolyte PEO and electrode active material SiO. This resulted in the enhanced ion conductivity and superior hardness in comparison to the pure SiO anodes, correspondingly, an increase in the diffusion coefficient and the electronic conductivity of the fabricated SiO electrode is realized. The optimized anodes, achieves 5.0 A/g rate property with 300 cycles stable cycling and a capacity retention ratio of 82%. This study offers valuable insights into the rational design of cost-effective and high specific energy SiO-based solid-state lithium-ion batteries.

Hybrid Molecular Sieve-Based Interfacial Layer with Physical Confinement and Desolvation Effect for Dendrite-free Zinc Metal Anodes.

The side reactions and dendrite growth at the interface of Zn anodes greatly limit their practical applications in Zn metal batteries. Herein, we propose a hybrid molecular sieve-based interfacial layer (denoted as Z7M3) with a hierarchical porous structure for Zn metal anodes, which contains 70 vol % microporous ZSM-5 molecular sieves and 30 vol % mesoporous MCM-41 molecular sieves. Through comprehensive molecular dynamics simulations, we demonstrate that the mesopores (∼2.5 nm) of MCM-41 can limit the disordered diffusion of free water molecules and increase the wettability of the interfacial layer toward aqueous electrolytes. In addition, the micropores (∼0.56 nm) of ZSM-5 can optimize the Zn2+ solvation structures by reducing the bonded water molecules, which simultaneously decrease the constraint force of solvated water molecules to Zn2+ ions, thus promoting the penetrability and diffusion kinetics of Zn2+ ions in Z7M3. The synergetic effects from the hybrid molecular sieves maintain a constant Zn2+ concentration on the surface of the Zn electrode during Zn deposition, contributing to dendrite-free Zn anodes. Consequently, Z7M3-coated Zn electrodes achieved excellent cycling stability in both half and full cells.

Effect analysis on the hydrocarbon adsorption performance enhancement of the different zeolite molecular sieves in the gasoline engine under the cold start process

In this work, the adsorption performance of ZSM-5, Beta-A, and NON zeolites on hydrocarbons emitted from the engine is investigated for selecting the best suited zeolite molecular sieves for hydrocarbon traps during the cold-start phase of the engine. Based on the giant canonical Monte Carlo (MC) method for adsorption simulation, the single-component, multi-component maximum adsorption, adsorption isotherms, adsorption sites of different hydrocarbon molecules on ZSM-5, Beta-A, and NON molecular sieves were investigated by using C2H2, C2H4, C3H6, and C7H8 molecules as probe molecules. The single-component adsorption results showed that for the macromolecular hydrocarbon toluene (C7H8) Beta-A zeolite had the best adsorption effect, followed by ZSM-5 zeolite, and NON had the worst adsorption effect. The adsorption of propylene (C3H6) on ZSM-5 and Beta-A is close to each other, and the adsorption of ethylene (C2H4) and acetylene (C2H2) are much different relative to C3H6 and C7H8. This is due to the fact that the adsorption properties of zeolites are determined by the molecular diameter of the hydrocarbons. The results of multicomponent adsorption showed that the adsorption amounts of multicomponent competitive adsorption were reduced relative to single-component adsorption, but were affected by other components in different ways, from small to large C7H8<C3H6<C2H4<C2H2.

Selective Heterogeneous Fenton Degradation of Formaldehyde Using the Fe-ZSM-5 Catalyst.

As a toxic Volatile Organic Pollutant (TVOC), formaldehyde has a toxic effect on microorganisms, consequently inhibiting the biochemical process of formaldehyde wastewater treatment. Therefore, the selective degradation of formaldehyde is of great significance in achieving high-efficiency and low-cost formaldehyde wastewater treatment. This study constructed a heterogeneous Fe-ZSM-5/H2O2 Fenton system f or the selective degradation of target compounds. By immobilizing Fe3+ onto the surface of a ZSM-5 molecular sieve, Fe-ZSM-5 was prepared successfully. XRD, BET and FT-IR spectral studies showed that Fe-ZSM-5 was mainly composed of micropores. The influences of different variables on formaldehyde-selective heterogeneous Fenton degradation performance were studied. The 93.7% formaldehyde degradation and 98.2% selectivity of formaldehyde compared with glucose were demonstrated in the optimized Fenton system after 360 min. Notably, the resultant selective Fenton oxidation system had a wide range of pH suitability, from 3.0 to 10.0. Also, the Fe-ZSM-5 was used in five consecutive cycles without a significant drop in formaldehyde degradation efficiency. The use of reactive oxygen species scavengers indicated that the hydroxyl radical was the primary active species responsible for degrading formaldehyde. Furthermore, great degradation performance was acquired with high concentrations of formaldehyde for this system, and the degradation efficiency was more than 95.0%.

Synergetic effect of green synthesized NZVI@Chitin-modified ZSM-5 for efficient oxidative degradation of tetracycline

The aggregation and limited activity of nanoscale zero-valent iron (NZVI) in aqueous media hinder its practical application. In this study, a cost-effective, environmentally friendly, robust, and efficient synthesis method for NZVI-based composite was developed. NZVI@Chitin-modified ZSM-5 (NZVI@C-ZSM) composite was facilely and greenly synthesized by loading NZVI into alkali-modified ZSM-5 molecular sieves after modifying with chitin as a surfactant and binder. NZVI@C-ZSM exhibited remarkable efficacy in TC removal, achieving a removal efficiency of 97.72% within 60 min. Compared with pristine NZVI, NZVI@C-ZSM demonstrated twice the removal efficiency, indicating that NZVI@C-ZSM effectively improved the dispersion and stability of NZVI. This enhancement provided more reactive sites for generating reactive oxygen species (ROS), significantly boosting catalytic activity and durability while reducing the potential risk of secondary pollution. An improved two-parameter pseudo-first-order kinetic model was used to effectively characterize the reaction kinetics. The mechanism for TC removal primarily involved an adsorption process and chemical oxidation-reduction reactions induced by hydroxyl radicals (•OH) and superoxide radicals (•O2−). Three potential degradation pathways for TC were suggested. Furthermore, NZVI@C-ZSM exhibited good resistance to interference, suggesting its broad potential for practical applications in complex environmental conditions. This study offers a viable material and method for addressing the issue of antibiotic-contaminated water, with potential applications in water resource management.

Synthesis of hierarchical Fe-incorporated ZSM-5 molecular sieves with an Fe-based metal-organic framework as a mesoporogen and iron source for catalytic pyrolysis of alkanes

To increase the yield of light olefins during the catalytic pyrolysis of alkanes, a novel hierarchical Fe-incorporated ZSM-5 molecular sieve (FeM-Z5) was synthesized using an Fe-based metal-organic framework (Fe-MOF) as a mesoporogen and iron source through the dry gel conversion (DGC) method. In contrast to the conventional method of incorporating Fe species into ZSM-5 via impregnation, the DGC method incorporates Fe species into the framework of ZSM-5, decreasing the amount of Brønsted (B) acid sites and thereby inhibiting the side reactions of hydrogen transfer during the catalytic pyrolysis of alkanes. Compared with the FeN-Z5 catalyst prepared by the DGC method with Fe(NO3)3 as an iron source, FeM-Z5 had a larger amount of strong B acid sites and more mesopores with a size range of 10–40 nm originating from the decomposition of Fe-MOF; these aspects improved n-pentane pyrolysis and ethylene and propylene diffusion. As a result, the optimal FeM-Z5 catalyst exhibited the highest yield of ethylene and propylene (33.4 wt%) and the lowest deactivation rate (0.07 %/h) among the prepared catalysts during the catalytic pyrolysis of n-pentane.

Spatial isolation effect improves the acidity and redox capacity of ZSM-5 encapsulating Pt catalyst to achieve efficient toluene oxidation

This paper introduces a novel approach of encapsulating Pt nanoparticles within the pores of a molecular sieve. By comparing the dispersion, reducibility and surface acid sites, the effect of the combination of molecular sieves and Pt particles on the catalytic performance of toluene was studied. The findings demonstrate that Pt nanoparticles were encapsulated within the molecular sieve framework of ZSM-5 molecular sieves using an in-situ synthesis method, exhibiting remarkable catalytic activity towards toluene oxidation (T90=172 ℃). Mainly due to the spatial confinement of the ZSM-5 molecular sieve framework reduces the size of Pt nanoparticles, enhances their dispersion of the Pt@ZSM-5 catalysts. In addition, the space separation effect of ZSM-5 on Pt metal enhances their interaction and promotes the valence state conversion of Pt species. It leads to a large number of acid sites and oxygen vacancies in the catalyst, which improves the adsorption and migration of toluene, thereby improving the catalytic activity. This study will provide valuable insights into the preparation of new nanocatalysts and the catalytic treatment of toluene.

Exploring the effect of polyacrylamide/graphene oxide composite hydrogel on the synthesis and application of ZSM-5 molecular sieves

Herein, we demonstrate the synthesis of coffin-shaped ZSM-5 molecular sieves in polyacrylamide (PAM)/graphene oxide (GO) composite hydrogel using the hydrothermal method. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), and Thermogravimetry analyses (TGA). The effect of PAM and GO addition on the morphology and structure of ZSM-5 was investigated. The results indicated that the introduction of PAM and GO promoted the growth of the ZSM-5 (101) plane. Moreover, samples synthesized in the PAM/GO hydrogel exhibited a longer c-axis and a more pronounced coffin-shaped morphology compared to samples synthesized solely in PAM hydrogel. The Si/Al ratio decreased with the addition of GO, possibly due to interface effects leading to the formation of ZSM-5 precursors with a higher Al content. TG, FT-IR, and XPS characterization revealed hydrogen bonding interactions between PAM and GO, and the addition of GO likely restricted the movement of polymers, improving cross-linking between monomers and forming a more uniform network structure. The sample G-15 (P-5) exhibited higher mesopore volume and average pore diameter, contributing to enhanced catalytic performance. However, with increasing GO content, the average pore diameter decreased, potentially due to functional groups on the surfaces of graphene oxide and polyacrylamide forming a more uniform and structurally stable three-dimensional network structure. This allowed for controlled modulation of the molecular sieve morphology and pore size. The introduction of PAM/GO hydrogel resulted in a moderate amount of weak acid and an increased amount of strong acid, both shifting to lower temperatures. The ZSM-5 molecular sieves synthesized in the PAM/GO composite hydrogel demonstrated outstanding MTO catalytic performance, exhibiting high selectivity for light olefins and an extended catalytic lifespan. This work is expected to provide new ideas and methods for developing efficient ZSM-5 catalysts.

Preparation of Porous ZSM-5 Molecular Sieve from Coal Gangue and Study on Its Adsorption Performance

Preparation of Porous ZSM-5 Molecular Sieve from Coal Gangue and Study on Its Adsorption Performance

Preparation and characterization of ZSM-5 molecular sieve using coal gangue as a raw material via solvent-free method: Adsorption performance tests for heavy metal ions and methylene blue

Coal gangue is a kind of solid waste produced in the process of coal mining and washing. Its silicon aluminum silicon aluminum oxide content is high, respectively, which are suitable for resource utilization as raw materials for Si–Al molecular sieving. In this paper, a novel, simple, low-cost, and environmentally friendly process was carried out to prepare ZSM-5 zeolite by solvent free method after calcination, acid leaching, and alkali melting. The obtained samples were characterized by Energy Dispersive Spectrometer (EDS), Inductively Coupled Plasma (ICP), Thermo-gravimetry Analysis (TG), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectrometer (FTIR) X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and N2 adsorption isotherm. The characteristics of the raw materials and the adsorption mechanism of the prepared samples were characterized. Through a series of pretreatment such as calcined acid leaching and alkali melting of the raw materials, the silicon-aluminum ratio of the sample reaches 1.749, and the maximum specific surface area of the sample can reach 252.59 m2/g. The obtained samples were used to adsorb heavy metal ions and methylene blue solution, and the removal rate of lead ions and methylene blue solution was more than 95%. The theoretical maximum adsorption capacity of Pb ion, methylene blue solution and copper ion can reach 232.56 mg/g and 118.34 mg/g. The adsorption process is mainly chemical adsorption. The product could be suitable for removing both heavy metal ions and cationic dyes from the wastewater and had broad application prospects.

Preparation of ZSM-5 molecular sieve modified by kaolin and its CO2 adsorption performance investigation

The ZSM-5 molecular sieve was prepared by the crystal species-assisted hydrothermal synthesis method using kaolin as raw material, and the molecular sieve were prepared by monometallic Na, Ni and bimetallic Ni–Na modification of the molecular sieve when using the isovolumetric impregnation method. It was found that the modified molecular sieve maintained the MFI structure of ZSM-5 molecular sieve, some mesopores appeared, and Na and Ni were uniformly dispersed on the inner and outer surfaces of the carrier by using XRD, ICP, FI-IR,UV–vis and BET. Moreover the presence of Na could increase the loading of metallic Ni. The effect of the modified molecular sieve on the CO2 adsorption performance was investigated using CO2 programmed temperature rise desorption (CO2-TPD). Na and Ni modification can increase the number of adsorption centers and improve the activity of adsorption centers on the surface of the adsorbent. Then Ni as an additive can enhance the interaction between metal and carrier, increase the density of active sites on the molecular sieve surface, and improve the adsorption performance on CO2. Among them, 1.5 Ni-0.6 Na/ZSM-5 adsorption has the better performance for CO2 adsorption with the bettert adsorption capacity of 1.97 mmol/g, which is 74% higher than ZSM-5, 84% higher than 2 Ni/ZSM-5, and 25% higher than 0.6 Na/ZSM-5.

Improvement of selenium adsorption performance at high temperature by CaO/ZSM-5 composite sorbents

ABSTRACT Selenium in flue gas from coal combustion, released into the atmosphere, will affect the environment and human health greatly. The adsorption method can achieve good control of selenium emission, by using CaO as adsorbent, but CaO is easy to sinter at high temperature, resulting in the decrease of adsorption capacity. Therefore, thermostability ZSM-5 molecular sieve was added to prepare composite adsorbent to improve the adsorption performance for selenium at high temperature. CaO/ZSM-5 composite adsorbent was prepared by impregnation method, and its adsorption performance and mechanism were studied. The results show that the composite adsorbent shows stronger adsorption capacity at high temperatures. The mixing ratio has a great influence on the microstructure of the composite adsorbent influencing the adsorption capacity. When the ratio is 1:1, the adsorption efficiency of the composite adsorbent shows a good performance. At 900°C, the adsorption efficiency of Z1C1(ZSM-5/CaO = 1:1 wt%) can still maintain 67%, which is 32% higher than that of CaO. Si and Al in the composite adsorbent have different effects on the improvement of microstructure. The existence of Si is conducive to maintaining the stable skeleton of the composite adsorbent, improving anti-sintering, while the addition of Al tends to improve the porosity, furtherly ameliorating the structure of the composite adsorbent for high-temperature adsorption.

Preparation of a High-Silicon ZSM-5 Molecular Sieve Using Only Coal Gangue as the Silicon and Aluminum Sources.

The traditional preparation of ZSM-5 molecular sieves relies on chemical reagents to provide silicon and aluminum sources, which are limited as raw materials and cannot be commonly used in production practice. Using coal gangue as the raw material and using medium-temperature chlorination roasting and the pressure acid leaching process to control the silicon-aluminum ratio [n(Si/Al)] of coal gangue, a ZSM-5 molecular sieve was prepared using the alkali melting hydrothermal method. The pressure acid leaching process solved the limitation that kaolinite and mica cannot simultaneously be activated. Under optimal conditions, the n(Si/Al) of the coal gangue increased from 6.23 to 26.14 and complied with the requirements for the synthesis n(Si/Al) of a ZSM-5 molecular sieve. The effect of n(Si/Al) on the preparation of the ZSM-5 molecular sieve was studied. Finally, spherical granular ZSM-5 molecular sieve material with a microporous specific surface area of 169.6329 m2/g, an average pore diameter of 0.6285 nm, and a pore volume of 0.0988 cm3/g was prepared. Providing ideas for the high-value utilization of coal gangue, it is significant for solving the problem of coal gangue solid waste, as well as the problem of ZSM-5 molecular sieve feed stock.

Insight into the catalytic oxidation of toluene over M/ZSM-5 (M=Cu, Mn, Fe, Ce, Ti) catalysts

A series of metal oxide catalysts were prepared by impregnating Cu, Mn, Fe, Ce and Ti on ZSM-5 molecular sieve. The physicochemical properties of the catalysts were characterized by SEM, XRD, N2 adsorption/desorption, XPS, H2-TPR, and the catalytic oxidation of toluene was investigated. The results showed that Cu/ZSM-5 had rough surface, uniform distribution of metal, good pore structure, superior low-temperature reducibility and abundant adsorbed oxygen species. Cu/ZSM-5 with 5% loading exhibited excellent catalytic activity for toluene oxidation and the best sulfur resistance performance, with t90 (GHSV=24000 h−1) being 224 °C in SO2 environment. In-situ DRIFTS experiments revealed that the degradation path of toluene was as follows: toluene was first adsorbed on the surface of the catalyst to form adsorbed toluene, then it was converted into benzaldehyde and benzoic acid successively on the catalyst. And small molecule organics such as maleic acid and carboxylic acid were formed through ring opening reaction, and finally was oxidized to CO2 and H2O.

Catalytic hydrothermal liquefaction of Chinese herb residue for the production of high-quality bio-oil

In this study, the catalytic hydrothermal liquefaction technology was adopted to convert the Chinese herb residue (CHR) into liquid bio-oil. The effect of the reaction conditions was investigated including temperature, water/biomass mass ratio (W/B) and time. Different combinations of Fe, Ni and ZSM-5 molecular sieve catalyst were evaluated to improve the bio-oil quality. The optimized liquefaction parameters were determined through experiments, which were the reaction temperature of 320 °C, W/B of 15:1, and reaction time of 10 min; the yield and high heat value (HHV) of bio-oil were 24.7 wt% and 29.39 MJ/kg, respectively. There was a synergy between Fe and ZSM-5, and Fe/ZSM-5 can achieve in situ hydrodeoxygenation in the liquefaction process, increasing the HHV of bio-oil to 31.74 M J/kg at 10 wt% loading with the yield of 21.3 wt%. The enhancement of bio-oil quality by Ni/ZSM-5 was weak due to the cleavage of C–C bond by Ni, resulting in the poor HHV and a low yield; the catalytic performance of Fe–Ni/ZSM-5 was between the former two catalysts. Elemental analysis and GC-MS showed that Fe/ZSM-5 increased H/C and decreased O/C in bio-oil, and the content of aliphatic compounds in bio-oil increased to 72.96%. • Chinese herb residue can be efficiently utilized by hydrothermal liquefaction. • Reaction temperature and W/B have a significant effect. • The operating conditions were given for highest yields of bio-oil. • Fe/ZSM-5 exhibits synergistic effect of hydrodeoxygenation. • 10 wt% Fe/ZSM-5 increases the HHV of bio-oil to 31.74 MJ/kg.

Iodine capture by ZSM-5 with different Si/Al ratios: An experimental and molecular simulation investigation

In order to capture radioactive iodine from nuclear power waste gas, the performance and mechanism of iodine capture by ZSM-5 molecular sieves were analyzed in this paper by experiments and molecular simulations. The results of the experiment showed that the iodine adsorption capacity increased with the increasing Si/Al ratio of the ZSM-5, and rose and then fell with increasing temperature. After four adsorption-desorption cycles, it could still maintain good morphology and adsorption performance (83.17%–90.61%). The molecular simulation results found that as the Si/Al ratio increased, the average bond length of the I–I bond increased, the adsorption energy increased, the interaction between iodine and molecular sieve increased, and the adsorption capacity of iodine increased, which was consistent with the experimental results. In this study, the capture process and adsorption mechanism of iodine were further understood, and it provides a favorable scheme for the treatment of nuclear waste gas.

COx hydrogenation to methanol and other hydrocarbons under mild conditions with Mo3S4@ZSM-5

The hydrogenation of CO2 or CO to single organic product has received widespread attentions. Here we show a highly efficient and selective catalyst, Mo3S4@ions-ZSM-5, with molybdenum sulfide clusters ([Mo3S4]n+) confined in zeolitic cages of ZSM-5 molecular sieve for the reactions. Using continuous fixed bed reactor, for CO2 hydrogenation to methanol, the catalyst Mo3S4@NaZSM-5 shows methanol selectivity larger than 98% at 10.2% of carbon dioxide conversion at 180 °C and maintains the catalytic performance without any degeneration during continuous reaction of 1000 h. For CO hydrogenation, the catalyst Mo3S4@HZSM-5 exhibits a selectivity to C2 and C3 hydrocarbons stably larger than 98% in organics at 260 °C. The structure of the catalysts and the mechanism of COx hydrogenation over the catalysts are fully characterized experimentally and theorectically. Based on the results, we envision that the Mo3S4@ions-ZSM-5 catalysts display the importance of active clusters surrounded by permeable materials as mesocatalysts for discovery of new reactions.

Analysis of the structural and environmental impacts of hydrophilic ZSM-5 molecular sieve on loess

Foundation treatment is an essential pre-work for the building construction. Recently, a lot of attention has been paid to loess stabilizers, due to the wide distribution of loess deposits. In this work, ZSM-5 molecular sieve is firstly applied as a loess stabilizer, with the aim of investigating its stabilizing and environmental performance. The unconfined compression strength (USC) and shear strength envelope of hydrophilic ZSM-5 molecular sieve stabilized loess (ZSL) samples with different ZSM-5 molecular sieve contents are measured, showing that the strength of ZSL samples is significantly enhanced. The reasons for the changes in mechanical properties are explained by a microstructural interpretation considering different aspects of ZSL sample microstructure, including cementation strength, mineral analysis, morphological, pore, and elemental composition. Based on the experimental evidence of the changes induced by stabilization on microstructure and mechanical properties, two categories are then defined in terms of ZMS-5 content, and a schematic diagram of the stabilization mechanism is provided. The environmental impacts of the loess stabilization process achieving similar shear strength with ZSM-5 molecular sieve, lime, and cement are figured out and compared by life cycle assessment. The research proves that the stabilization method with ZSM-5 molecular sieve is characterized a better environmental performance in terms of greenhouse gas emission. By analyzing the contribution of every material used in the production of ZSM-5 molecular sieve, a more environmentally friendly and effective production strategy has been finally proposed, which can promote the diffusion of ZSM-5 molecular sieve in the market of loess foundation stabilization.