Alkanolamines are the most popular absorbents used to remove CO 2 from process gas streams. Therefore, the CO 2 reaction with alkanolamines is of considerable importance. The aim of this article is to provide an overview on the kinetics of the reaction of CO 2 with aqueous solutions of alkanolamines. The various reaction mechanisms that are used to interpret experimental kinetic data -zwitterion, termolecular and base-catalyzed hydration -are discussed in detail. Recently published data on reaction kinetics of individual amine systems and their mixtures are considered. In addition, the kinetic behavior of several novel aminebased solvents that have been proposed in the literature is analyzed. Generally, the reaction of CO 2 with primary, secondary and sterically hindered amines is governed by the zwitterion mechanism, whereas the reaction with tertiary amines is described by the base-catalyzed hydration of CO 2 .

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Glycerol, which is obtained as a by‐product in biodiesel production, represents a candidate source of hydrogen that is renewable. Its conversion into hydrogen can be achieved by a reforming process. In this article, the glycerol reforming reaction is reviewed. Different reforming processes for hydrogen production, viz. steam, aqueous, and autothermal reforming, are described in brief. The thermodynamic analyses, which enable comparison with experimental studies, are considered. A discussion on experimental investigations over several catalysts is presented, too. Many reaction pathways are possible and some of them are dependent on the properties of the catalyst used. Generally, Ni, Pt, and Ru catalysts facilitate hydrogen production. The same catalysts are also effective for the reforming reaction of ethanol – another renewable resource for hydrogen. While ethanol steam reforming has been comprehensively reviewed by now, an overview on glycerol reforming is still missing. In this paper, an evaluation of the published studies is given to close this gap.

Aqueous solutions containing alkaline salts of carboxylic or sulfonic amino acids represent candidate solvents with good potential for carbon dioxide (CO2) capture. In the present work, the CO2 reactions with potassium salts of glycine (aminoacetic acid) and taurine (2-aminoethanesulfonic acid) in aqueous solutions are investigated using a stirred-cell reactor. The reaction pathways are comprehensively described using the zwitterion and the termolecular mechanism. The investigated reactions belong to the fast pseudo-first-order reaction regime systems. The second-order rate constant for the CO2 reaction with potassium glycinate is determined, and its value at 303 K is evaluated to be 6.29 m3/(mol s). The liquid-side mass-transfer coefficient is estimated, and its value (0.006 cm/s) is consistent with those typical for stirred-cell reactors. Finally, it is determined that potassium glycinate promotes the activity of tertiary amines (e.g., N,N-diethylethanolamine).

Bio-oil from biomass fast pyrolysis can be transformed into hydrogen (H2) or alkanes (C1–C6) by aqueous phase processing (APP). Low temperature hydrogenation of the water-soluble portion of bio-oil is a useful intermediate step of APP. In the present work, the anhydrosugar levoglucosan (LG) was selected as a model compound of the bio-oil aqueous fraction. LG hydrogenation was studied in a slurry reactor using heterogeneous Ru/C catalyst. Kinetic data were obtained experimentally in the range of temperatures, 398 to 433 K, H2 partial pressures, 0.69 to 2.07 MPa, initial LG concentrations, 0.6 to 3.1 mM and catalyst loading, 0.5 to 1.5 kg/m3. Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetics was used for modeling initial rates of LG disappearance. Two kinetic models assuming that surface reaction is rate-controlling reasonably represented the kinetic data. Model 1 assumed competitive adsorption of dissociatively chemisorbed H2 and LG, whereas model 2 was based on competitive adsorption of molecular H2 and LG. However, model II seemed to be not feasible, because of the low activation energy value and the assumption of reaction with molecular H2.

Catalytic steam reforming of ethanol over a Ru/γ-Al 2 O 3 catalyst in the temperature range 873-973 K was studied. The influence of inlet ethanol concentration on ethanol conversion and hydrogen yield was investigated. The conversion vs space time data was subjected to the integral method of analysis. The results show that the reaction order with respect to ethanol is 1. An activation energy of 96 kJ mol -1 was obtained. A possible reaction sequence for ethanol steam reforming was suggested. A rate expression was derived assuming that the decomposition of an activated complex formed during reaction into intermediate products was the ratedetermining step.

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