Conversion of propane or butanes from natural/shale gas into propene or butenes, which are indispensable for the synthesis of commodity chemicals, is an important environmentally friendly alternative to oil-based cracking processes. Herein, we critically analyse recent developments in the non-oxidative, oxidative, and CO2-mediated dehydrogenation of propane and isobutane to the corresponding olefins over metal oxide catalysts. Particular attention is paid to (i) comparing the developed catalysts in terms of their application potential, (ii) structure-activity-selectivity relationships for tailored catalyst design, and (iii) reaction-engineering aspects for improving product selectivity and overall process efficiency. On this basis, possible directions for further research aimed at the development of inexpensive and environmentally friendly catalysts with industrially relevant performance were identified. In addition, we provide general information regarding catalyst preparation and characterization as well as some recommendations for carrying out non-oxidative and CO2-mediated dehydrogenation reactions to ensure unambiguous comparison of catalysts developed in different studies.

Current status and perspectives in oxidative, non-oxidative and CO2-mediated dehydrogenation of propane and isobutane over metal oxide catalysts.

Current advances in membrane technologies for saline wastewater treatment: A comprehensive review

In heterogeneous catalysis, unravelling the distinct structural and compositional nature of active sites provides a good platform in modulating important catalytic properties toward improved activity and selectivity. Obviously, despite the direct propane dehydrogenation (PDH) being a commercial process, oxidative dehydrogenation of propane (ODHP) remains a highly prospective technology for propene production due to its leveraged thermodynamic advantage and less susceptibility to catalyst deactivation. The present work has systematically and comprehensively reviewed recent advances on key aspects related to ODHP catalysts such as nature of the active sites, active sites isolation, accessibility of active sites, active sites in layered-double hydroxide (LDH) derived mixed oxide catalysts, intercalated LDH precursors, co-precipitated LDH precursors, oxides-support interaction, oxygen vacancy, surface oxide reducibility, and acid–base property. Furthermore, discussion on accelerated discovery of novel catalysts via high-throughput experimentations (HTE) and high-throughput quantum computations (HTC) has been provided. Integrated frameworks via machine learning and Python language are hugely augmenting in this pursuit. It is hoped that this perspective provides insights on the design and tuning of heterogeneous catalysts, and in particular the development of efficient catalysts that could prompt industrialization and commercialization of ODHP process.

Catalyst design and tuning for oxidative dehydrogenation of propane – A review

Multi-defects engineering of NiCo2O4 for catalytic propane oxidation

An ever-increasing volume of saline effluents from industries, oil–gas fields, and desalination plants has resulted in an enormous amount of pollutants with undesirable effects on the environment and human health. Adequate disposal and treatment of these effluents remains a persistent problem and poses significant technical as well as economic challenges. Saline effluents can have considerable environmental impacts, depending upon the sensitivity of the surrounding ecosystems. Conventional disposal techniques mostly suffer from direct or indirect contamination of water/soil and are no longer preferred. As a result, several advanced treatment methods are being considered for sustainable saline effluent management in recent times. In this context, a comprehensive and updated review of conventional methods, along with emerging technologies for disposal and treatment of saline effluent, is presented. Existing treatment approaches, including membrane operation, thermal processes, chemical techniques, and biological methods, are discussed. The application of innovative hybrid processes (combining two or more treatment methods) aiming at lower energy demand and higher treatment efficiency has also been evaluated. Subsequently, emerging sustainable strategies like waste minimization and water recovery, zero liquid discharge, and resource recovery for saline effluents have been examined. The prospect of integrating the renewable energy sources with energy-intensive saline treatment methods towards energy–water– environment nexus is also explored.

A comprehensive review of saline effluent disposal and treatment: conventional practices, emerging technologies, and future potential

Calcined silica-supported sodium decavanadate (Na6V10O28/SiO2) is more active for the oxidative dehydrogenation of propane (ODP) than the thermodynamically stable α-polymorph of sodium metavanadate...

Reducibility and Dispersion Influence the Activity in Silica-Supported Vanadium-Based Catalysts for the Oxidative Dehydrogenation of Propane: The Case of Sodium Decavanadate

A pilot-scale hybrid membrane system, consisting of a ceramic microfilter (MF), two differentpolyvinyl chloride (PVC) and polyacrylonitrile (PAN) ultrafilters (UF), and a polyamide reverse osmosis (RO) filter, has been utilized to decrease harmful and damaging components in wastewater produced from Tehran Refinery with aim to be reused at boilers and cooling towers. Taguchi method was employed to find optimum operating conditions including transmembrane pressure, cross flow velocity (CFV), temperature, and backwash time. Further, analysis of variance (ANOVA) was performed to determine the significance of controlling factors on total organic carbon rejection and normalized permeate flux. MF (ceramic)/UF (PVC) system reduced, %: oil 99.7; chemical oxygen demand (COD) 82; biochemical oxygen demand (BOD) 79.3; conductivity 60.5; total dissolved solids (TDS) 52.6; turbidity 99.7 and total hardness 73.2. MF(ceramic)/UF (PAN) system reduced: oil, COD, BOD, conductivity, TDS, turbidity, and total hardness by 99.8; 84.2; 80.8; 62.72; 55; 99.9 and 78.4%, respectively. UF (PAN)/RO system decreased, %: oil 99.5; COD 99; BOD 99; conductivity 98; TDS 98; turbidity 98.7 and total hardness 99.94. Obtained treated wastewater by this system can be reused as feed water of boilers.

Feasibility of Treatment of Refinery Wastewater by a Pilot Scale MF/UF and UF/RO System for Reuse at Boilers and Cooling Towers

Zn-based Al2O3-suported materials have been proposed as inexpensive and environmentally friendly catalysts for the direct dehydrogenation of propane (PDH), however, our understanding of these catalysts’ structure and deactivation routes is still limited. Here, we correlate the catalytic activity for PDH of a series of Zn-based Al2O3 catalysts with their structure and structural evolution. To this end, three model catalysts are investigated. (i) ZnO/Al2O3 prepared by atomic layer deposition (ALD) of ZnO onto γ-Al2O3 followed by calcination at 700 °C, which yields a core-shell spinel zinc aluminate/γ-Al2O3 structure. (ii) Zinc aluminate spinel nanoparticles (ZnxAlyO4 NPs) prepared via a hydrothermal method. (iii) A reference core-shell ZnO/SiO2 catalyst prepared by ALD of ZnO on SiO2. The catalysts are characterized in detail by synchrotron X-ray powder diffraction (XRD), Zn K-edge X-ray absorption spectroscopy (XAS), and 27Al solid state nuclear magnetic resonance (ssNMR). These experiments allowed us to identify tetrahedral Zn sites in close proximity to Al sites of a zinc aluminate spinel phase (ZnIV–O–AlIV/VI linkages) as notably more active and selective in PDH relative to the supported ZnO wurtzite phase (ZnIV–O– ZnIV linkages) in ZnO/SiO2. The best performing catalyst, 50ZnO/Al2O3 gives 77% selectivity to propene (gaseous products based) at 9 mmol C3H6 gcat−1 h−1 space time yield (STY) after 3 min of reaction at 600 °C. On the other hand, the core-shell ZnO/Al2O3 catalyst shows an irreversible loss of activity over repeated PDH and air-regeneration cycles, explained by Zn depletion on the surface due to its diffusion into subsurface layers or the bulk. ZnxAlyO4 NPs gave a comparable initial selectivity and catalytic activity as 50ZnO/Al2O3. With time on stream, ZnxAlyO4 NPs deactivate due to the formation of coke at the catalyst surface, yet the extend of coke deposition is lower than for the ZnO/Al2O3 catalysts, and the activity of ZnxAlyO4 NPs can be regenerated almost fully using calcination in air.

Correlating the Structural Evolution of ZnO/Al2O3 to Spinel Zinc Aluminate with its Catalytic Performance in Propane Dehydrogenation

Background: Urmia Lake, the second largest hyper-saline lake of the world, has experienced lack of water and other environmental issues in recent years. Now, there is a danger of the lake drying out, which will affect the region and its inhabitants. This study aimed to present a model which can relate the water level of the lake to effective factors. 
Methods: Parameters that influence water level, such as precipitation, evaporation, water behind dams, and the previous year’s water level, were considered in the modeling procedure. The proposed model, based on evolutionary polynomial regression, can be used to evaluate salt marshes produced in the region in recent years. 
Results: Results show that the high surface-area-to-depth ratio of Urmia Lake is most influential on its drying; however, omitting this characteristic as an inherent one, the main cause is the construction of dams on rivers in the Urmia Lake basin. 
Conclusion: The proposed model predicts that by 2015, the water level of Urmia Lake will fall below 1269 m, and by 2030, the lake will dry out completely.

Drying of urmia lake: modeling of level fluctuations

Urmia Lake’s water surface area is among the most important parameters needed for water balance analysis. Periodical measurement of this parameter directly by conventional topography almost seems impossible since it is costly and time – consuming. Such limitations highlight the needs for new approaches to be taken, namely remote sensing technique which could provide a good approximation of lake’s surface area in terms of some other parameters available or at least easily measured. This paper considers development of a new model for lake’s surface area measurement according to available water levels and its comparison with other methods in this field as well as the calculations regarding salt-land formation and coastline changes. High resolution images provided by NASA satellites, Aqua and Terra were collected and passed an image processing stage through MATLAB software for surface area calculations. Finally, the water level and surface area values resulted from the home made code, were put together to reach relationship. The comparison between the results of proposed method and provided data by Eastern Azerbaijan Water Organization and also a similar study indicated that the proposed image processing technique has good performance to estimate the surface area of Urmia Lake. The maximum error between the results of proposed model and a similar study which was used combination method of Cellular Automata and Markov Chain was 5.96 % which indicates the good performance of image processing technique in estimation of surface area of Urmia Lake.

http://arww.razi.ac.ir/article_399_73e458da13337eb3cdc66244d7da8364.pdf

Manouchehr Nadjafi

Papers

Reducibility and Dispersion Influence the Activity in Silica-Supported Vanadium-Based Catalysts for the Oxidative Dehydrogenation of Propane: The Case of Sodium Decavanadate

Feasibility of Treatment of Refinery Wastewater by a Pilot Scale MF/UF and UF/RO System for Reuse at Boilers and Cooling Towers

Correlating the Structural Evolution of ZnO/Al2O3 to Spinel Zinc Aluminate with its Catalytic Performance in Propane Dehydrogenation

Drying of urmia lake: modeling of level fluctuations

Forecasting Surface Area Fluctuations of Urmia Lake by Image Processing Technique