scholarly journals Improved Kinetics and Water Recovery with Propane as Co-Guest Gas on the Hydrate-Based Desalination (HyDesal) Process

2019 ◽  
Vol 3 (1) ◽  
pp. 31 ◽  
Author(s):  
Abhishek Nambiar ◽  
Ponnivalavan Babu ◽  
Praveen Linga
Keyword(s):  
Sodium Dodecyl ◽  
Fixed Bed ◽  
Hydrate Formation ◽  
High Water ◽  
Gas Mixtures ◽  
Fixed Bed Reactor ◽  
Water Recovery ◽  
Thermal Desalination ◽  
Cold Energy ◽  
Desalination Technology

Water is a key resource for sustainable development and plays a crucial role in human development. Desalination is one of the most promising technologies to mitigate the emerging water crisis. Thermal desalination and reverse osmosis are two of the most widely employed desalination technologies in the world. However, these technologies are energy intensive. Clathrate-hydrate-based desalination (HyDesal) is a potential energy-efficient desalination technology to strengthen the energy–water nexus. In our previous study, we proposed a ColdEn-HyDesal process utilizing waste Liquefied Natural Gas (LNG) cold energy based on a fixed-bed reactor configuration. In this study, we evaluated the effect of 10% propane in three different gas mixtures, namely, nitrogen (G1), argon (G2), and carbon dioxide (G3), as hydrate formers for the HyDesal process. The achieved water recovery was very low (~2%) in the presence of NaCl in the solution for gas mixtures G1 and G2. However, high water recovery and faster kinetics were achieved with the G3 mixture. To improve the water recovery and kinetics of hydrate formation for the G2 gas mixture, the effect of sodium dodecyl sulfate (SDS) was evaluated. The addition of SDS did improve the kinetics and water recovery significantly.

scholarly journals MgO Dispersed on Activated Carbon as Water Tolerant Catalyst for the Conversion of Ethanol into Butanol

2019 ◽  
Vol 9 (7) ◽  
pp. 1371 ◽  
Author(s):  
Stefano Cimino ◽  
Jessica Apuzzo ◽  
Luciana Lisi
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Fixed Bed ◽  
High Water ◽  
Fixed Bed Reactor ◽  
High Dispersion ◽  
Water Tolerance ◽  
Butanol Yield

MgO supported on activated carbon (AC) with a load ranging from 10% to 30% has been investigated as catalyst for the conversion of ethanol into butanol at 400 °C in a fixed bed reactor at different GHSV. Catalysts have been characterized by XRD, SEM/EDX, and N2 physisorption at 77 K. The high dispersion of MgO into the pores of the support provides strongly enhanced performance with respect to bulk MgO. MgO/AC catalysts have been also tested under wet feed conditions showing high water tolerance and significantly larger butanol yield with respect to an alumina supported Ru/MgO catalyst. After wet operation, the increased surface area of the catalyst leads to better performance once dry feed conditions are restored.

Hydrate-Based Carbon Capture Process: Assessment of Various Packed Bed Systems for Boosted Kinetics of Hydrate Formation

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Amit Arora ◽  
Asheesh Kumar ◽  
Gaurav Bhattacharjee ◽  
Chandrajit Balomajumder ◽  
Pushpendra Kumar
Keyword(s):  
Carbon Dioxide ◽  
Carbon Capture ◽  
Carbon Dioxide Capture ◽  
Fixed Bed ◽  
Hydrate Formation ◽  
Packed Bed ◽  
Fixed Bed Reactor ◽  
Capture Process ◽  
Novel Technologies ◽  
Kinetics Of

Abstract The case for developing novel technologies for carbon dioxide (CO2) capture is fast gaining traction owing to increasing levels of anthropogenic CO2 being emitted into the atmosphere. Here, we have studied the hydrate-based carbon dioxide capture and separation process from a fundamental viewpoint by exploring the use of various packed bed media to enhance the kinetics of hydrate formation using pure CO2 as the hydrate former. We established the fixed bed reactor (FBR) configuration as a superior option over the commonly used stirred tank reactor (STR) setups typically used for hydrate formation studies by showing enhanced hydrate formation kinetics using the former. For the various packing material studied, we have observed silica gel with 100 nm pore size to return the best kinetic performance, corresponding to a water to hydrate conversion of 28 mol% for 3 h of hydrate growth. The fundamental results obtained in the present study set up a solid foundation for follow-up works with a more applied perspective and should be of interest to researchers working in the carbon dioxide capture and storage and gas hydrate fields alike.

PdIn Catalysts in a Continuous Fixed Bed Reactor for the Nitrate Removal from Groundwater

2019 ◽  
Vol 17 (6) ◽  
Author(s):  
F. A. Marchesini ◽  
G. Mendow ◽  
N. P. Picard ◽  
F. M. Zoppas ◽  
V. S. Aghemo ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalyst Deactivation ◽  
Catalytic Reduction ◽  
Bubble Column ◽  
Catalyst Activity ◽  
Nitrate Removal ◽  
Fixed Bed ◽  
High Water ◽  
Fixed Bed Reactor ◽  
Water Volume

Abstract The ground water (GW) is a real sample of water which contains nitrates (81 mg/L), carbonates and sulphates. This sample was treated by catalytic reduction in a bubble column fixed-bed reactor. The reaction conditions were room temperature and atmospheric pressure, and hydrogen was used as reducing agent. A comparison between the catalytic activity of Pd,In/SiO2 and Pd,In/Al2O3 catalysts was performed, giving the latter the best results regarding the nitrate conversion and the former the selectivity to nitrogen. Synthetic water containing nitrates (SW) and the groundwater (GW) with high salinity (81 mg/L nitrates) and humic acid content were treated in these conditions using HCl and CO2 as acidifiers. When the SW was acidified with CO2 at an H2 flow (2.17 mL/min), more than 50 % of conversion was obtained with an ammonia and nitrite concentrations of 0.44 and 0.92 ppm respectively. These results reached the level established by the WHO and the USEPA. However, both Pd,In/SiO2 and Pd,In/Al2O3 catalysts showed evidence of some deactivation process. This deactivation was higher in the GW sample, possibly due to the presence of Ca+2 and Mg+2 cations that precipitate on the active sites, and/or the presence of humic acids. The characterization studies indicated that, after the reaction, the composition of the metal phases was modified, specifically on their surface. As the catalyst activity is related to surface ratio Pd/In, a relative increase in the concentration of Pd decreases the activity and causes changes in the selectivity to N2. Some sintering of the metal particles was also observed to contribute to catalyst deactivation. Nevertheless, promising results were obtained since a high water volume could be treated with a relatively low amount of low metal loading catalysts.

Impact of Modified Silica Beads on Methane Hydrate Formation in a Fixed-Bed Reactor

2019 ◽  
Vol 58 (36) ◽  
pp. 16687-16695 ◽  
Author(s):  
Florian Filarsky ◽  
Carsten Schmuck ◽  
Heyko Juergen Schultz
Keyword(s):  
Methane Hydrate ◽  
Fixed Bed ◽  
Hydrate Formation ◽  
Fixed Bed Reactor ◽  
Modified Silica ◽  
Silica Beads

scholarly journals Efek Zeolit untuk Produksi Tar dan Char pada Pirolisis Rotary Kiln

2021 ◽  
Vol 12 (1) ◽  
pp. 51
Author(s):  
Widya Wijayanti
Keyword(s):  
Heat Transfer ◽  
Rotary Kiln ◽  
Fixed Bed ◽  
Mesh Size ◽  
High Water ◽  
Fixed Bed Reactor ◽  
High Water Content ◽  
Pyrolysis Process ◽  
Pyrolysis Products ◽  
Biomass Decomposition

<p class="00textwithtab">This study aims to investigate the effect of zeolite as a catalyst to enlarge biomass decomposition in the pyrolysis process. It absorbs a high water content in the biomass, besides it makes the easier breaking of biomass molecules to maximize the biomass decomposition into the expected pyrolysis products; tar and char. In addition, to decompose the biomass molecules, the zeolite also stimulates the rate of heat transfer due to its ability to hold and release the heat. If the previous research pyrolysis was conducted in a fixed bed reactor, in this study, it will be carried out rotary kiln as a pyrolysis furnace. If the fixed bed reactor the heat transfer was dominated by conduction, the heat transfer in the rotary kiln is more controlled by the convection and radiation transfer due to stirring and turning of biomass by the kiln. In the study, the biomass used was mahogany with an initial weight of 150 grams. The rotary kiln rotated at 10 rpm and the heating rate during the pyrolysis process was around 0.1483°C/s. The pyrolysis temperatures used were varied as 250°C, 350°C, 450°C. Meanwhile, the percentage of zeolites used from 0% to 60% with a mesh size of 80. The results showed that zeolites were able to increase tar production and maximize the reduction of char as an effect of the Bronsted-Lowry and Lewis reaction in the process of catalytic cracking. The maximum production of tar and char production was also supported by the process of convection and radiation from the rotary kiln wall increasing the rate of heat transfer to decompose the biomass.</p><p class="02abstracttext"> </p>

scholarly journals The Feasibility of Binary and Ternary Hydrate Mixtures of CH4, CO2 and C3H8 for Metals Removal

2021 ◽  
Author(s):  
Hani Abulkhair ◽  
Abdulmohsen Alsaiari ◽  
Iqbal Ahmad ◽  
Sirisha Nallakukkala ◽  
Bhajan Lal ◽  
...  
Keyword(s):  
Driving Force ◽  
Binary Systems ◽  
Hydrate Formation ◽  
Ternary Systems ◽  
High Water ◽  
Ternary Mixtures ◽  
Water Recovery ◽  
Gas Composition ◽  
Metals Removal ◽  
Binary And Ternary Mixtures

Abstract The selection of suitable hydrate formers and their respective gas composition for high hydrate formation driving force is critical to achieve high water recovery and metals removal efficiency in the hydrate-based desalination process. This study presents a feasibility analysis on the possible driving force and subcooling temperatures for the binary and ternary mixtures of methane, carbon dioxide, and propane for hydrates-based desalination process. The driving force and subcooling of the gas systems was evaluated by predicting their hydrate formation phase boundary conditions in 2 wt.% NaCl systems at pressures ranges from 2.0 - 4.0 MPa and temperatures of 1 – 4°C using Modified Peng-Robinson Equation of State in the PVTSim software package. The results suggested that the driving force of CH4-C3H8 and CO2+C3H8 binary systems are similar to their ternary. Thus, the use of binary systems is preferable and simpler than the ternary systems. For binary gas composition CO2+C3H8 (70:30) exhibited a higher subcooling temperature of 8.07 ºC and driving force of 1.49 MPa in presence of 2wt% salt. In case of ternary system (CH4-C3H8-CO2) composition of (10:80:10) provided a good subcooling temperature of 12.86 ºC for hydrate formation. The results favour CO2-C3H8 as preferred hydrate formers for hydrate- based desalination. This is attributed due to the formation of sII structure and as it constitutes 136 water molecules which signifies a huge potential of producing more quantity of treated water.

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