| 1. |
- Bernas, Andreas, et al.
(författare)
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Catalytic transformation of abietic acid to hydrocarbons
- 2012
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Ingår i: Topics in catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 55:7-10, s. 673-679
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Tidskriftsartikel (refereegranskat)abstract
- Catalytic and thermal conversion of abietic acid was investigated in a laboratory scale high-pressure autoclave. Fractionation of crude tall oil produces rosin acids of which abietic acid is the main compound. Tall oil rosin acid, a forest product industry residue, is an abundant, inexpensive and chemically desirable feedstock for production of lighter hydrocarbons that can be used as diesel fuel additives. The carboxylic acid functionality of the main reactant, abietic acid, must first be removed, followed by double bond hydrogenation of the remaining aromatic rings. In this study, a number of catalytic and non-catalytic reaction steps in the conversion of abietic acid were investigated. The aim was to study hydrogenation and decarboxylation reactions of abietic acid in order to produce lighter hydrocarbons. The experiments were performed by using toluene as a solvent as well as with neat abietic acid, in the absence of any solvent. Hydrogenation of abietic acid to tetrahydroabietic acid in toluene was successfully performed over palladium on carbon catalyst at the temperature range of 100-200 A degrees C and at 30 bar hydrogen pressure. Thermal non-catalytic decarboxylation of abietic acid in toluene takes place at 200-300 A degrees C resulting in one main product. The hydrocarbon products were further hydrogenated under hydrogen pressure. Catalytic decarboxylation of abietic acid in toluene was achieved over 5 wt% Ru/C, giving a wider product distribution than thermal decarboxylation.
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| 2. |
- de Araujo Filho, Cesar Augusto, et al.
(författare)
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Kinetic model for homogeneously catalyzed halogenation of glycerol
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:4, s. 1523-1530
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Tidskriftsartikel (refereegranskat)abstract
- A new kinetic model for the halogenation of polyalcohols, e.g. chlorination of glycerol with gaseous HCl in the presence of homogeneous acid catalysts was developed. The model is based on a reaction mechanism, which includes esterification and epoxidation steps followed by halogenation steps. The principle of quasi-steady state was applied to the ester and ionic intermediates appearing in the model and rate equations were derived. Furthermore, some simplified cases of the rate equations were considered, such as immediate water removal from the reaction mixture and analytical solutions for the simplified kinetic models were derived. The model was verified against experimental data obtained from laboratory-scale semibatch reactors. The conclusion is that the model worked very well, predicting correctly the glycerol conversion and the product distribution of α-, β-, α,β- and α,γ-chlorinated products. The kinetic model can be used for design of reactors for homogeneously catalyzed halogenation.
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| 3. |
- Jung, Christian, et al.
(författare)
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A comparison of very old patients admitted to intensive care unit after acute versus elective surgery or intervention
- 2019
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Ingår i: Journal of critical care. - : W B SAUNDERS CO-ELSEVIER INC. - 0883-9441 .- 1557-8615. ; 52, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Background: We aimed to evaluate differences in outcome between patients admitted to intensive care unit (ICU) after elective versus acute surgery in a multinational cohort of very old patients (80 years; VIP). Predictors of mortality, with special emphasis on frailty, were assessed.Methods: In total, 5063 VIPs were induded in this analysis, 922 were admitted after elective surgery or intervention, 4141 acutely, with 402 after acute surgery. Differences were calculated using Mann-Whitney-U test and Wilcoxon test. Univariate and multivariable logistic regression were used to assess associations with mortality.Results: Compared patients admitted after acute surgery, patients admitted after elective surgery suffered less often from frailty as defined as CFS (28% vs 46%; p < 0.001), evidenced lower SOFA scores (4 +/- 5 vs 7 +/- 7; p < 0.001). Presence of frailty (CFS >4) was associated with significantly increased mortality both in elective surgery patients (7% vs 12%; p = 0.01), in acute surgery (7% vs 12%; p = 0.02).Conclusions: VIPs admitted to ICU after elective surgery evidenced favorable outcome over patients after acute surgery even after correction for relevant confounders. Frailty might be used to guide clinicians in risk stratification in both patients admitted after elective and acute surgery.
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| 4. |
- Salmi, Tapio, et al.
(författare)
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Fine chemicals from glycerol : Modelling of homogeneously catalyzed halogenation
- 2012
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Ingår i: CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference PRES.
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Konferensbidrag (refereegranskat)abstract
- A new kinetic model for the halogenation of polyalcohols, e.g. chlorination of glycerol with gaseous HCl in the presence of homogeneous acid catalysts was developed. The model was based on a reaction mechanism, which includes esterification and epoxidation steps followed by halogenation steps. Some simplified cases of the rate equations were considered, e.g., immediate water removal from the reaction mixture and analytical solutions for the simplified kinetic models. The model worked very well, predicting correctly the glycerol conversion and the product distribution of chlorinated products. The kinetic model can be used for design of reactors for homogeneously catalyzed halogenation. This is an abstract of a paper presented at the CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference PRES (Prague, Czech Republic 8/25-29/2012).
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