Reactive distillation for cosmetic ingredients : an alternative for the production of isopropyl myristate?

This thesis starts with a brief overview of the current production processes for fatty acid esters. Because these processes have several drawbacks, a new technology is proposed: Entrainer-based Reactive Distillation. In Entrainer-based Reactive Distillation, in situ separation is used to improve the yield of reaction, whereas an entrainer feed is added to overcome the alcohol-water azeotrope, by selectively increasing the relative volatility of water. The objective of this research is the development of a multi-product Entrainer-based Reactive Distillation process for the synthesis of fatty acid esters using a heterogeneous catalyst, and evaluate its attractiveness compared to the current technologies. In Chapter 2 it is demonstrated that, due to the similarities between Entrainer-based Reactive Distillation and azeotropic distillation, the same selection rules can be applied to select a suitable entrainer. From a list of suitable entrainers for the azeotropic distillation of isopropanol and water, cyclohexane and isopropyl acetate are chosen. Residue curve maps, simulations of the distillation section of the column, and simulations of the total Entrainer-based Reactive Distillation concept show that both can be used as an entrainer in Entrainer-based Reactive Distillation. Whether Entrainer-based Reactive Distillation will be feasible, strongly depends on the kinetics of the reaction. For this reason Chapter 3 discusses the reaction kinetics of the esterification of myristic acid with isopropanol and with n-propanol, using sulphated zirconia (SZ) and ( p)-toluene sulphonic acid (pTSA) as catalysts, for a temperature range of 343-403K. SZ appeared to be an unsuitable catalyst for the esterification of myristic acid with isopropanol since it did not increase the reaction rate of the uncatalysed reaction. For the reactions with pTSA the reaction rates are determined. The reactions follow first order kinetics in all components. The kinetic model corresponds with the results for the esterification of myristic acid with isopropanol and the results for the esterification of palmitic acid from literature. As expected, the reaction rate increases with increasing amount of catalyst and with increasing temperature. The reaction rate and equilibrium conversion increases with an increasing alcohol to myristic acid feed ratio. The reaction with n-propanol is considerably faster (at 373K about 3.8 times) than the reaction with isopropanol. On the basis of the entrainer selection and kinetics studies Chapter 4 will discuss the gains that can be obtained using Entrainer-based Reactive Distillation with regard to conventional Reactive Distillation. Five process configurations for the esterification of myristic acid with isopropanol and ( n)-propanol using a homogeneous catalyst, are compared, by simulation in Aspen Plus. In the esterification with isopropanol at 1 bar, the addition of the entrainer has no positive influence on the conversion, because the amount required for water removal causes temperature decrease in the column. This temperature decrease has a negative in°uence on the conversion, because the high activation energy of the reaction cannot be overcome. However, in the esterification with iso-propanol at 5 and 10 bar and in the esterification with n-propanol (either 1, 5 or 10 bar), the addition of the entrainer has a positive influence on the conversion. More entrainer leads to a higher conversion. Surprising is the observation that the conventional Reactive Distillation configuration (RD1) reaches the desired purity and conversion. Because of its polarity, water is pressed out of the liquid phase, in which the reaction takes place, so the reaction can reach nearly complete conversion. Because the decrease of the reaction volume due to the addition of the entrainer is rather small and the energy consumption is comparable, conventional Reactive Distillation (RD1) is the preferable configuration for the esterification of myristic acid with either isopropanol or n-propanol. Subsequently, the Aspen Plus process for the reactive distillation is validated through pilot plant experiments in Chapter 5. A detailed model of the pilot plant is created for different operating conditions. Experiments with a pilot column are performed to verify the model. The conducted experiments correspond well with the predicted values; the model can be used in the construction of a conceptual design. However, not all the intended validation experiments could be performed, because of the practical difficulties that arise when negligible liquid level in the column has to be ensured. Also the break down of the pumps due to clogging appeared a limiting factor in the experiments.Finally, the process model from Chapter 5 is used to construct a conceptual design for the esterification of myristic acid with isopropanol through reactive distillation (packed, tray and bubble column). A parameter optimisation study is performed to investigate the influence of the different process parameters. Finally all results are integrated in conceptual designs for the industrial scale processes, which are evaluated against the batch process based on required reaction volumes. The required reaction volume can be decreased with 27 or 79%, allowing a maximum temperature of respectively 170 and 220ºC, using a packed reactive distillation column. Using a tray reactive distillation column and a maximum temperature of 220ºC, the required reaction volume can be decreased with 93%. Due to the less favourable mass transfer characteristics, in the bubble column the required reaction volume can only be decreased with 78%. It is further noted that, at a temperature of 220ºC, the tray reactive distillation is the preferable process for the esterification of myristic acid isopropanol, based on the required reaction volumes. The influence of the maximum column temperature and the influence of a larger liquid hold-up per stage as a result of a different column configuration are of equal importance for the required reaction volume. This thesis shows that reactive distillation can be used for the production of isopropyl myristate, which results in an enormous decrease in reaction volume compared to the batch process. Therefore, it can be concluded that reactive distillation has the potential to become an economically attractive alternative, not only for fatty acid esters based on methanol and primary alcohol which is already known, but also for the production of isopropyl myristate

An atomic force microscope operating at hypergravity for in situ measurement of cellular mechano-response

We present a novel atomic force microscope (AFM) system, operational in liquid at variable gravity, dedicated to image cell shape changes of cells in vitro under hypergravity conditions. The hypergravity AFM is realized by mounting a stand-alone AFM into a large-diameter centrifuge. The balance between mechanical forces, both intra- and extracellular, determines both cell shape and integrity. Gravity seems to be an insignificant force at the level of a single cell, in contrast to the effect of gravity on a complete (multicellular) organism, where for instance bones and muscles are highly unloaded under near weightless (microgravity) conditions. However, past space flights and ground based cell biological studies, under both hypogravity and hypergravity conditions have shown changes in cell behaviour (signal transduction), cell architecture (cytoskeleton) and proliferation. Thus the role of direct or indirect gravity effects at the level of cells has remained unclear. Here we aim to address the role of gravity on cell shape. We concentrate on the validation of the novel AFM for use under hypergravity conditions. We find indications that a single cell exposed to 2 to 3 × g reduces some 30–50% in average height, as monitored with AFM. Indeed, in situ measurements of the effects of changing gravitational load on cell shape are well feasible by means of AFM in liquid. The combination provides a promising technique to measure, online, the temporal characteristics of the cellular mechano-response during exposure to inertial forces

Age-dependent differences in the pathogenesis of bovine respiratory syncytial virus infections related to the development of natural immunocompetence

The severity of respiratory syncytial virus (RSV) infections appears to differ with age in both humans and bovines. A primary RSV infection in naïve infants and in young calves runs a more severe course when they are 1–6 months old than in their first month of life. The relative lack of clinical signs in the first month of age may be due to high levels of maternally derived neutralizing antibodies or low exposure to infectious virus. This study examined whether age-dependent differences in the pathogenesis of bovine RSV (bRSV) between neonatal and young calves may be due to differences in age-dependent immunocompetence. To study the effect of age and immune parameters on bRSV disease in neonatal and young calves, neonatal (1-day-old) calves without maternally derived antibodies were infected experimentally with bRSV and the severity of disease and immune responses were evaluated in comparison with disease in similar 6-week-old infected calves. Neonatal calves had more extensive virus replication and lung consolidation, but lower pro-inflammatory [in particular tumour necrosis factor alpha (TNF-{alpha})] responses, specific humoral immune responses, lung neutrophilic infiltration and clinical signs of disease than 6-week-old calves. The lack of correlation between virus replication and clinical signs suggests an important role of pro-inflammatory cytokines, in particular TNF-{alpha}, in the disease. The capacity to produce pro-inflammatory TNF-{alpha} appeared to increase with age, and may explain the age-dependent differences in RSV pathogenesis

Інвестиційні чинники формування інтегративної моделі економічного розвитку європейських країн

Contains fulltext : 130547.pdf (publisher's version ) (Open Access

The public's voice about healthcare quality regulation policies. A population-based survey

Background: In the wake of various high-profile incidents in a number of countries, regulators of healthcare quality have been criticised for their 'soft' approach. In politics, concerns were expressed about public confidence. It was claimed that there are discrepancies between public opinions related to values and the values guiding regulation policies. Although the general public are final clients of regulators' work, their opinion has only been discussed in research to a limited extent. The aim of this study is to explore possible discrepancies between public values and opinions and current healthcare quality regulation policies. Methods: A questionnaire was submitted to 1500 members of the Dutch Healthcare Consumer Panel. Questions were developed around central ideas underlying healthcare quality regulation policies. Results: The response rate was 58.3 %. The regulator was seen as being more responsible for quality of care than care providers. Patients were rated as having the least responsibility. Similar patterns were observed for the food service industry and the education sector. Complaints by patients' associations were seen as an important source of information for quality regulation, while fewer respondents trusted information delivered by care providers. However, respondents supported the regulator's imposition of lighter measures firstly. Conclusions: There are discrepancies and similarities between public opinion and regulation policies. The discrepancies correspond to fundamental concepts; decentralisation of responsibilities is not what the public wants. There is little confidence in the regulator's use of information obtained by care providers' internal monitoring, while a larger role is seen for complaints of patient organisations. This discrepancy seems not to exist regarding the regulator's approach of imposing measures. A gradual, and often soft approach, is favoured by the majority of the public in spite of the criticism that is voiced in the media regarding this approach. Our study contributes to the limited knowledge of public opinion on government regulation policies. This knowledge is needed in order to effectively assess different approaches to involve the public in regulation policies