scholarly journals Novel Ni-Co-Mo-K Catalysts Supported on Multiwalled Carbon Nanotubes for Higher Alcohols Synthesis

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Venkateswara Rao Surisetty ◽  
Janusz Kozinski ◽  
Ajay Kumar Dalai
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Synthesis Gas ◽  
Space Velocity ◽  
Molar Ratio ◽  
Higher Alcohols ◽  
Multiwalled Carbon ◽  
Ni Content ◽  
Trimetallic Catalyst ◽  
Higher Alcohols Synthesis

Alkali-promoted Ni-Co-Mo catalysts supported on multiwalled carbon nanotubes (MWCNTs) were prepared using 9 wt% K, 4.5 wt% Co, and 15 wt% Mo, whereas Ni content was varied from 0 to 6 wt%. The catalysts were extensively characterized and studied for higher alcohols synthesis from synthesis gas. Alkali-promoted trimetallic catalyst with 3 wt% Ni showed the highest total alcohols yield of 0.284 gm/(gm of cat./h), ethanol selectivity of 20%, and higher alcohols selectivity of 32% at 330°C and 9.0 MPa using gas hourly space velocity (GHSV) of 3.8 m3 (STP)/kg of catalyst/h and H2 to CO molar ratio of 1.25.

scholarly journals Comparing the Adsorption Performance of Multiwalled Carbon Nanotubes Oxidized by Varying Degrees for Removal of Low Levels of Copper, Nickel and Chromium(VI) from Aqueous Solutions

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 723 ◽  
Author(s):  
Marko Šolić ◽  
Snežana Maletić ◽  
Marijana Kragulj Isakovski ◽  
Jasmina Nikić ◽  
Malcolm Watson ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Carbon Nanotubes ◽  
Aqueous Solutions ◽  
Multiwalled Carbon Nanotubes ◽  
Electrostatic Interactions ◽  
Positive Impact ◽  
Molar Ratio ◽  
Multiwalled Carbon ◽  
Removal Of Heavy Metals ◽  
Low Levels

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has on the ability of MWCNTs to treat water contaminated with low levels of Cu(II), Ni(II) and Cr(VI) (initial concentrations 0.5–5 mg L−1) and elucidates the adsorption mechanisms involved. Adsorbent characterization showed that the molar ratio of C and O in these materials was slightly lower for the oxMWCNT6h, due to the higher degree of oxidation, but the specific surface areas and mesopore volumes of these materials were very similar, suggesting that prolonging the functionalization duration had an insignificant effect on the physical characteristics of oxidized multiwalled carbon nanotubes (oxMWCNTs). Increasing the Ph of the solutions from Ph 2 to Ph 8 had a large positive impact on the removal of Cu(II) and Ni(II) by oxMWCNT, but reduced the adsorption of Cr(VI). However, the ionic strength of the solutions had far less pronounced effects. Coupled with the results of fitting the kinetics data to the Elowich and Weber–Morris models, we conclude that adsorption of Cu(II) and Ni(II) is largely driven by electrostatic interactions and surface complexation at the interface of the adsorbate/adsorbent system, whereas the slower adsorption of Cr(VI) on the oxMWCNTs investigated is controlled by an additional chemisorption step where Cr(VI) is reduced to Cr(III). Both oxMWCNT3h and oxMWCNT6h have high adsorption affinities for the heavy metals investigated, with adsorption capacities (expressed by the Freundlich coefficient KF) ranging from 1.24 to 13.2 (mg g−1)/(mg l−1)n, highlighting the great potential such adsorbents have in the removal of heavy metals from aqueous solutions.

Effect of Operating Conditions for Higher Alcohols Synthesis from Synthesis Gas over Alkali-Modified Co-Rh-Mo Trimetallic Catalyst Supported on Multi-Walled Carbon Nanotubes

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Venkateswara Rao Surisetty ◽  
Janusz Kozinski ◽  
Ajay K. Dalai
Keyword(s):  
Carbon Nanotubes ◽  
Synthesis Gas ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Optimum Operating ◽  
Higher Alcohols ◽  
Higher Alcohols Synthesis ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The effects of operating conditions on the higher alcohols synthesis reaction from synthesis gas were studied in a single-pass tubular downflow fixed-bed reactor, using sulfided K-promoted trimetallic Co-Rh-Mo catalyst supported on multi-walled carbon nanotubes (MWCNTs). The p CO conversion increased monotonically with increasing reaction temperature (from 275 to 350°C) and pressure (from 800 to 1400 psi), while decreasing monotonically with increasing GHSV (from 2.4 to 4.2 m3 (STP)/(kg of cat./h)). To maximize the ethanol STY and selectivity, the optimum operating conditions were determined as 330°C, 1320 psi, and 3.8 m3 (STP)/kg of cat./h). Maximum ethanol STY and selectivity were obtained using gas with H2 to CO molar ratio around 1.25.

Synthesis of Multiwalled Carbon Nanotubes

1999 ◽  
Vol 593 ◽  
Author(s):  
David Jacques ◽  
Stephane Villain ◽  
Apparao M. Rao ◽  
Rodney Andrews ◽  
Frank Derbyshire ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Iron Catalyst ◽  
Growth Parameters ◽  
Space Velocity ◽  
Operating Conditions ◽  
Multiwalled Carbon ◽  
Time Space ◽  
Quartz Substrates

ABSTRACTIn a recent publication we have described the synthesis of multiwalled carbon nanotubes (MWNTs) by the reaction of a hydrocarbon vapor over a dispersed iron catalyst that is deposited in situ on quartz substrates. Our system configuration involves entraining a mixture of xylene and ferrocene into an inert gas stream. Decomposition of the ferrocene at temperatures in the range 625-775 °C, and at atmospheric pressure, produces a coating of iron nanoparticles on the quartz surfaces, and these metal sites function as catalysts for the formation and growth of MWNTs. In this study, we report the influence of operating conditions on MWNT purity and yield. These parameters include the feed injection temperature, furnace temperature, hydrocarbon partial pressure, reaction time, space velocity, and iron to carbon ratio in the feed. We observed that the quality of the MWNTs dependc sensitively on the growth parameters and a window for the operating conditions is identified for the growth of high purity aligned MWNTs. Characterization of the MWNTs by electron microscopy has shown that there is a relationship between metal particle size and MWNT diameter.

Effect of Multiwalled Carbon Nanotubes On Mechanical Properties of Concrete

2012 ◽  
Vol 2 (6) ◽  
pp. 166-168 ◽  
Author(s):  
Dr.T.Ch.Madhavi Dr.T.Ch.Madhavi ◽  
◽  
Pavithra.P Pavithra.P ◽  
Sushmita Baban Singh Sushmita Baban Singh ◽  
S.B.Vamsi Raj S.B.Vamsi Raj ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon
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