Research Progress on the Indirect Hydrogenation of Carbon Dioxide to Methanol

Xian-Long Du, Zheng Jiang, Dang Shen Su, Jian-Qiang Wang

First published: 21 December 2015   DOI: 10.1002/cssc.201501013

Abstract

Methanol is a sustainable source of liquid fuels and one of the most useful organic chemicals. To date, most of the work in this area has focused on the direct hydrogenation of CO₂ to methanol. However, this process requires high operating temperatures (200–250 °C), which limits the theoretical yield of methanol. Thus, it is desirable to find a new strategy for the efficient conversion of CO₂ to methanol at relatively low reaction temperatures. This Minireview seeks to outline the recent advances on the indirect hydrogenation of CO₂ to methanol. Much emphasis is placed on discussing specific systems, including hydrogenation of CO₂ derivatives (organic carbonates, carbamates, formates, cyclic carbonates, etc.) and cascade reactions, with the aim of critically highlighting both the achievements and remaining challenges associated with this field.

http://onlinelibrary.wiley.com/doi/10.1002/cssc.201501013/full

Conversion of CO2 from Air into Methanol Using a Polyamine and a Homogeneous Ruthenium Catalyst

http://pubs.acs.org/doi/abs/10.1021/jacs.5b12354
 
Conversion of CO2 from Air into Methanol Using a Polyamine and a Homogeneous Ruthenium Catalyst
Jotheeswari Kothandaraman, Alain Goeppert, Miklos Czaun, G. K. Surya Prakash, and George A Olah
J. Am. Chem. Soc., Just Accepted Manuscript
DOI: 10.1021/jacs.5b12354
Publication Date (Web): December 29, 2015
Copyright © 2015 American Chemical Society

Abstract: A highly efficient homogeneous catalyst system for the continuous production of CH3OH from CO2 using PEHA and Ru-Macho-BH (1) at 125-165 °C in an ethereal solvent has been developed (initial TOF = 70 h-1 at 145 °C). Ease of separation of CH3OH is demonstrated by simple distillation from the reaction mixture. The robustness of the catalytic system was shown by recycling the catalyst over 5 runs without significant loss of activity (TON>2000 h-1). Various sources of CO2 can be used for this reaction including the air, despite its low CO2 concentration (400 ppm). For the first time, we have demonstrated that CO2 captured from air can be directly converted to CH3OH in 79% yield using the homogeneous catalytic system.

Mono- and tri-ester hydrogenolysis using tandem catalysis. Scope and mechanism

Mono- and tri-ester hydrogenolysis using tandem catalysis. Scope and mechanism 

Tracy L. Lohr,^a   Zhi Li,^a   Rajeev S. Assary,^b   Larry A. Curtiss^bc and   Tobin J. Marks*^a   

Energy Environ. Sci., 2016, Advance Article

DOI: 10.1039/C5EE03256C 

Received 23 Oct 2015, Accepted 26 Nov 2015

First published online 26 Nov 2015 

pubs.rsc.org/en/content/articlelanding/2016/ee/c5ee03256c#!divAbstract

Abstract: The scope and mechanism of thermodynamically leveraged ester RC(O)O–R′ bond hydrogenolysis by tandem metal triflate + supported Pd catalysts are investigated both experimentally and theoretically by DFT and energy span analysis. This catalytic system has a broad scope, with relative cleavage rates scaling as, tertiary > secondary > primary ester at 1 bar H₂, yielding alkanes and carboxylic acids with high conversion and selectivity. Benzylic and allylic esters display the highest activity. The rate law is ν = k[M(OTf)_n]¹[ester]⁰[H₂]⁰ with an H/D kinetic isotope effect = 6.5 ± 0.5, implying turnover-limiting C–H scission following C–O cleavage, in agreement with theory. Intermediate alkene products are then rapidly hydrogenated. Applying this approach with the very active Hf(OTf)₄ catalyst to bio-derived triglycerides affords near-quantitative yields of C₃ hydrocarbons rather than glycerol. From model substrates, it is found that RC(O)O–R′ cleavage rates are very sensitive to steric congestion and metal triflate identity. For triglycerides, primary/external glyceryl CH₂–O cleavage predominates over secondary/internal CH–O cleavage, with the latter favored by less acidic or smaller ionic radius metal triflates, raising the diester selectivity to as high as 48% with Ce(OTf)₃.