Solvent Effect in Liquid-Phase Hydrogenation of Toluene

Rautanen, Petri A.; Aittamaa, Juhani; Krause, A.O.I.

doi:10.1021/ie000349v

Cited by 47 publications

(45 citation statements)

References 21 publications

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“…Liquid phase hydrogenation reaction of toluene (C 7 H 8 ) on Ni/Al 2 O 3 showed higher rate using isooctane ((CH 3 ) 3 CCH 2 CH(CH 3 ) 2 ) and n-heptane (C 7 H 16 ) compared with cyclohexane (C 6 H 12 ) due to 40% lower hydrogen solubility in C 6 H 12 compared with other solvents. 22 However, solvent effects on hydrogenation reactions are not always dependent on solubility only. Other parameters such as solvent polarity, catalyst−solvent interactions, and solvent molecular structure may affect the reaction.…”

Section: ■ Introductionmentioning

confidence: 99%

Hydrogenation of Carbon Monoxide into Formaldehyde in Liquid Media

Bahmanpour

Hoadley

Mushrif

et al. 2016

ACS Sustainable Chem. Eng.

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Formaldehyde is a bulk chemical which is produced in excess of 30 million tons per annum and is growing in demand. However, the current production process requires methanol production, which is oxidized in air to produce formaldehyde, which must then be absorbed into water. Our recent work introduced a novel method to produce formaldehyde through CO hydrogenation in the aqueous phase. However, the aqueous phase has certain limitations which must be overcome to make it commercially viable. By applying a deuterium labeling technique and investigating the potential intermediates, the reaction mechanism was established which showed that solvents play a vital role in determining the yield. Various solvents were used for formaldehyde production, and the highest formaldehyde yield was achieved by using pure methanol followed by methanol−water mixtures. Formaldehyde reacts with methanol and water to produce hemiacetal and methylene glycol, respectively, thereby shifting the equilibrium of CO hydrogenation toward formaldehyde production. Methanol and water stabilize the hemiacetal and methylene glycol molecules, respectively, via hydrogen bonding. The highest yield of formaldehyde in methanol solvent was found to be 15.58 mmol L −1 g cat −1 at 363 K and 100 bar, which is four times higher than our previous report. The liquid phase method shown here has the potential to be greener and more sustainable than the commercial processes because it operates at low temperatures and results in 100% selectivity toward formaldehyde with no CO 2 generation. ■ INTRODUCTIONDue to the increasing global energy demand, many researchers have focused on reduction of energy consumption in the chemical industry. It is essential to search for more efficient, energy saving processes for the production of valuable chemicals. Many aspects can be considered and evaluated during process optimization. Increasing the conversion of reactants and product yield are often considered; however, process alternatives to save energy and capital costs are sometimes overlooked by researchers. Formaldehyde (HCHO) industrial production through methanol (CH 3 OH) partial oxidation dates back to 1882. 1 Since then, other methods of production such as methane (CH 4 ) partial oxidation 2−8 or CO 2 hydrogenation 9,10 were considered, but none were able to compete with the high conversion achieved by the methanol oxidation process. However, despite the high conversion of CH 3 OH and high selectivity toward HCHO, the industrial methods of HCHO production suffer from CO 2 generation as a byproduct 1 and a high energy consumption rate which leads to low exergy efficiency (43.2%). 11 A novel HCHO production method through direct CO hydrogenation in the aqueous phase using Ru−Ni/Al 2 O 3 was recently introduced, which could potentially increase the exergy efficiency with no CO 2 production, 12 as a result of bypassing the production of methanol and also the much lower reaction temperatures. However, it was not clear how the reaction proceeds in the aqueous phase. Although th...

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Section: ■ Introductionmentioning

confidence: 99%

Hydrogenation of Carbon Monoxide into Formaldehyde in Liquid Media

Bahmanpour

Hoadley

Mushrif

et al. 2016

ACS Sustainable Chem. Eng.

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“…Thus, we can assume that during the initial phase (similar to an induction period), the reaction proceeds via less reactive species yielding 100% selectivity, while highly reactive species responsible for the selectivity drop are being formed. After the initial phase, one can see a linear dependence indicating zero order with respect to DHL, which is often related to the strong adsorption of the substrate on the catalyst surface [81] . The TOF value was confi rmed to be constant and equal to 9.4 ± 0.3 s − 1 for all the studied SCRs.…”

Section: Kinetics Of Dhl Hydrogenationmentioning

confidence: 99%

Nanoparticulate Catalysts Based on Nanostructured Polymers

Bronstein

Matveeva

Sulman

2007

Nanoparticles and Catalysis

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The catalytic nanoparticles possess unique catalytic properties due to their large surface area and considerable number of surface atoms leading to an increased amount of active sites [1 -3] . The catalytic properties of nanoparticles depend on the nanoparticle size, nanoparticle size distribution, and nanoparticle environment [4] . Moreover, the surface of nanoparticles plays an important role in catalysis, being responsible for their selectivity and activity. As was demonstrated in the last decade, the formation of nanoparticles in a nanostructured polymeric environment allows enhanced control over nanoparticle characteristics, yet the stabilizing polymer (its functionality) is of great importance, determining the state of the nanoparticle surface [5 -8] .Recently, catalytic nanoparticles formed in various types of nanostructured polymers have been extensively studied in major catalytic reactions [5 -7] . Although traditional polymer -based catalysts may be faulted by such shortcomings as uncontrolled swelling or poor accessibility of nanoparticles in the polymer bulk, the nanostructured polymers are mainly free from these limitations due to the small size of the nanoparticle -containing zones. Moreover, some swelling can even be advantageous, providing better access to the nanoparticle surface. The majority of nanostructured polymers for catalytic applications are amphiphilic block copolymers and dendrimers while some other polymers have also been explored. The ability of amphiphilic block copolymers to form micelles in dilute solutions in selective solvents [9, 10] has been used to stabilize catalytic nanoparticles in the functionalized micelle cores [11,12] . Pd nanoparticles formed in PS -b -P4VP micelles were used as a catalyst for the cross -coupling reaction between aryl halides and alkenes (Heck reaction) [12] . These hybrid systems exhibited nearly the same effi ciency as low -molecular -mass palladium complexes (conventional catalysts of the Heck reaction), being at the same time much more stable. The PS -b -P4VP micelles containing Pd and Pd/Au nanoparticles were studied in the hydrogenation of cyclohexene, 1,3 -cyclooctadiene, and 1,3 -cyclohexadiene [11] . A strong infl uence of the synthetic pathway to form nanoparticles and the type of 93 Nanoparticles and Catalysis. Edited by Didier Astruc

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“…Meanwhile, in the catalytic hydrogenation reaction, the solvent has a great influence on the reaction rate and selectivity. Some studies have concluded that [37,38], for the similar structures solvent, the solubility of hydrogen in the solvent may affect the rate of heterogeneous catalytic hydrogenation, and the solvent may affect the adsorption of hydrogen on the catalyst surface in the catalytic hydrogenation reaction.…”

Section: Introductionmentioning

confidence: 99%