The high performance and mechanism of metal–organic frameworks and their composites in adsorptive desulfurization

A data driven machine learning approach for predicting and optimizing sulfur compound adsorption on metal organic frameworks

This study employed some machine learning (ML) techniques with Python programming to forecast the adsorption capacity of MOF adsorbents for thiophenic compounds namely benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyl dibenzothiophene (4,6-DMDBT). Five ML models were developed with the help of a dataset containing 676 rows to correlate the adsorbent features, adsorption conditions, and adsorbate characteristics to the MOF sample's sulfur adsorption capability. Among the ML approaches, MLP model achieved the best performance with a low mean squared error (MSE) of 0.0032 on the test set and 0.0021 on the training set and mean relative error (MRE) of 15.26% on the test set. Also, Random Forest model yielded a higher test MSE of 0.0045 and MRE of 17.83%. Feature importance analysis was performed by utilizing MLP model and shapely additive plan (SHAP) method, and the findings revealed that "initial concentration of sulfur" (SHAP value 0.51) and "contact time" (SHAP value 0.37) were the crucial factors influenced desulfurization process efficiency. Additionally, a comparative analysis of the features utilizing the MLP network classified the factors into three primary categories: process conditions, adsorbent characteristics, and adsorbate characteristics. Consequently, the process condition was identified as the most significant group compared to others. Finally, the desulfurization process optimization indicated the maximum DBT adsorption of 161.6 mg/g for Zr-based MOF could be achieved when the features including BET, TPV, pore size, oil/adsorbent ration, and temperature were tuned around 756 m2/g, 0.955 cm3/g, 5.96 nm, 449.85 g/g, 20.1 °C, respectively.

Assessment of polyethylene/Zn-ionic as a diesel fuel sulfur adsorbent: gamma radiation effect and response surface methodology

Irradiated waste high-density polyethylene@Zn/ionic liquid novel composite well-fabricated via coacervation method was irradiated by gamma-irradiation and studied the effect of that radiation on the desulfurization process. The prepared composites were characterized by various analytical techniques as follows: X-ray diffraction (XRD), Fourier-Transform infrared (FT-IR), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM), High Resolution Transmission Electron Microscopy (HRTEM), N₂-adsorption-desorption isotherm, and thermal gravimetric analysis (TG/DTA). The adsorptive desulfurization process of benzothiophene (BT) and dibenzothiophene (DBT) which are harmful compounds in diesel model fuel was investigating using the irradiated and unirradiated composite. The results illustrated that the unirradiated and irradiated composites exhibit an adequate adsorption capacity reached (50-75 mg S/g) and (60-85 mg S/g) for BT and DBT, respectively. The adsorption process over the prepared adsorbents follows the pseudo-second-order kinetic models. The irradiated composite exhibited more adsorption capacity than the unirradiated one due to the radiation generated more surface area and created proton-bond donor sites in the composite surface, which increases the interaction between the surface and sulfur species. The adsorption capacity and adsorption percentage for irradiated and unirradiated composites towards (SCCs) were studied using response surface methodology based on the central composite design (CCD). The thermodynamic factors (∆H°, ∆G°, and ∆S°) reveal that these processes are endothermic adsorption processes. The irradiated PEt @Zn/IL was re-used without significant loss of adsorption activity. This novel irradiated PEt @Zn/IL is the first time used as an adsorbent with an advantage that includes its excellent adsorption capacity, which ensures the product will be efficient in a real process such as the petrochemical industry.

Metal Organic Frameworks as Desulfurization Adsorbents of DBT and 4,6-DMDBT from Fuels

Ultradeep desulfurization of fuels is a method of enormous demand due to the generation of harmful compounds during the burning of sulfur-containing fuels, which are a major source of environmental pollution. Among the various desulfurization methods in application, adsorptive desulfurization (ADS) has low energy demand and is feasible to be employed at ambient conditions without the addition of chemicals. The most crucial factor for ADS application is the selection of the adsorbent, and, currently, a new family of porous materials, metal organic frameworks (MOFs), has proved to be very effective towards this direction. In the current review, applications of MOFs and their functionalized composites for ADS are presented and discussed, as well as the main desulfurization mechanisms reported for the removal of thiophenic compounds by various frameworks. Prospective methods regarding the further improvement of MOF's desulfurization capability are also suggested.

Research advancements in sulfide scavengers for oil and gas sectors

Sulfide species (inorganic and organic sulfides) are well known for their toxicity and corrosiveness. Several industries, including oil and gas, are prone to corrosive damage due to sulfides that necessitate their timely removal using appropriate methods. Employing chemical scavengers is the most suitable method where the scavenger combine with dissolved sulfides in aqueous/hydrocarbon phase and convert them to a nontoxic and less corrosive form that can be easily removed from the stream. Instead of direct chemical scavenger addition, different approaches, including absorption and adsorption methods, are employed in eliminating sulfide species from gas streams in different industrial applications. This review provides a detailed account of various sulfide scavengers used in oil and gas sweetening. Most recent research advancements in this area are highlighted. A brief account of the latest reported works on novel adsorbents for the desulfurization process for refinery fuels is also provided. The review ends with a short discussion on catalytic hydrodesulfurization.

Metal organic framework-graphene nano-composites for high adsorption removal of DBT as hazard material in liquid fuel

Nowadays, one of the most important energy issues is how to deal with the sulfur removal from liquid fuels in a simple and inexpensive ways. Adsorptive desulphurization process can solve this issue when use highly effective adsorbent like metal organic frameworks (MOFs) and its nano-composites. In this context, this study uses the green solvo-themal method for the preparation of MOF (Cu-BTC) and MOF/Graphene hybrid nano-composite to be used as an effective DBT adsorbent from the model fuels. The prepared adsorbents were characterized by using different analytical techniques like: XRD, FTIR, BET, and TEM. Adsorption experimental results demonstrated that the composite material MOF/Gr (9:1 wt ratio) exhibited extra ordinary high dibenzothiophene adsorption with adsorption capacity (46.2 mg S/g) under the optimum experimental conditions. Kinetic and Langmuir and Freundlich isotherm were also studied.

High removal of thiophene from model gasoline by porous MIL-101(Cr)/SA hybrid membrane

Membrane separation technologies have great promising potential for applications in several industries. Metal-organic frameworks (MOFs), for their large surface areas, low framework densities, transition-metal ions in the skeleton and high pore volumes relative to other porous matrices, have great potential for the removal of sulfur from gasoline with high efficiency. In the present study, a novel porous membrane adsorbent MIL-101(Cr)/SA was prepared by immobilizing MIL-101(Cr) onto sodium alginate (SA) matrix, which can combine the size/shape selectivity of MIL-101(Cr) with the processability and mechanical stability of SA polymer. The physico-chemical properties of MIL-101(Cr)/SA were investigated by FT-IR, SEM, BET, XRD and EDX methods. To investigate the effects of some important factors on the adsorption behavior for thiophene, a batch of experiments were performed by changing the concentration of porogen polyethylene glycol in the MIL-101(Cr)/SA, solution temperature, initial thiophene concentration and contact time. Meanwhile, benzothiophene, thiophene and 3-methyl thiophene were used to test the selectivity of MIL-101(Cr)/SA. The MIL-101(Cr)/SA showed an excellent uptake capacity of 671 mg g-1 under the optimal adsorption conditions. Selectivity testing indicated that the uptake capacity of MIL-101(Cr)/SA follows the order of benzothiophene > thiophene > 3-methyl thiophene. Kinetics experiments indicated the pseudo-second-order model displayed good correlation with adsorption kinetics data. The Crank model showed that the intraparticle solute diffusion is the rate-controlling adsorption step. Regeneration experiment result shows that the prepared MIL-101(Cr)/SA has excellent adsorption and desorption efficiencies.