Application of Multiple Regression and Design of Experiments for Modelling the Effect of Monoethylene Glycol in the Calcium Carbonate Scaling Process.

To avoid gas hydrate formation during oil and gas production, companies usually employ thermodynamic inhibitors consisting of hydroxyl compounds, such as monoethylene glycol (MEG). However, these inhibitors may cause other types of fouling during production such as inorganic salt deposits (scale). Calcium carbonate is one of the main scaling salts and is a great concern, especially for the new pre-salt wells being explored in Brazil. Hence, it is important to understand how using inhibitors to control gas hydrate formation may be interacting with the scale formation process. Multiple regression and design of experiments were used to mathematically model the calcium carbonate scaling process and its evolution in the presence of MEG. It was seen that MEG, although inducing the precipitation by increasing the supersaturation ratio, actually works as a scale inhibitor for calcium carbonate in concentrations over 40%. This effect was not due to changes in the viscosity, as suggested in the literature, but possibly to the binding of MEG to the CaCO3 particles' surface. The interaction of the MEG inhibition effect with the system's variables was also assessed, when temperature' and calcium concentration were more relevant.

Continuous-flow synthesis of dimethyl fumarate: a powerful small molecule for the treatment of psoriasis and multiple sclerosis.

Dimethyl fumarate (DMF) is a methyl ester of fumaric acid and has recently gained attention due to its use as a pro-drug in different pharmaceutical preparations, besides the low price of the final molecule and no active patents being available for the synthesis of DMF, the prices of multiple sclerosis treatment are still high. In our continuous effort for the development of process intensification strategies towards the synthesis of active pharmaceutical ingredients, here we present our work on a cascade methodology for dimethyl fumarate synthesis in short reaction times and quantitative yields.

Controlling Nitrogen Oxide (NO x ) Emissions from Exothermic Nitrogen Generation Systems for Application in Subsea Environments.

A highly exothermic nitrogen generation system (NGS) can be achieved by mixing solutions of sodium nitrite and ammonium chloride, a process used by the oil and gas industry to dissolve paraffin wax and gas hydrates. Although its main products are nitrogen gas and a sodium chloride brine, the NGS has a side reaction that produces nitrogen oxides. To optimize this process to ensure the greatest and fastest heat generation with the lowest oxide production, this reaction was checked by infrared spectroscopy and calorimetry. The factors temperature, pH, and initial concentration of nitrite and ammonium were evaluated, and the optimal conditions of the NGS were determined by the constructed models to predict heat and NO x generation. These conditions were a ratio of ammonium/nitrite equal to 1 and a catalyst concentration of 0.07 mol·L-1 (for a case in which the temperature is 5 °C).

Effects of Solvent Polarity on the Reaction of Aldehydes and Ketones with a Hydrazide-Bound Scavenger Resin.

Polymer-supported reagents have been extensively studied and used in various applications, such as condensation reactions and multiple component reactions. This paper examines the reactions between a solid-functionalized resin, named Amb15-Iso, and aldehydes and ketones that have been solubilized in different solvents. The reactions between these molecules and a hydrazide (isoniazid) in both neutral and acidic media were also studied. The results showed that the solvent polarity influenced the kinetics of the reaction and the yields of carbonyl compounds that were captured by the resin, particularly, for less-reactive molecules. The reactions using the resin were faster than those using free isoniazid in solution, likely because the acidic sites remaining in the resin can catalyze the reaction, increasing the rate of capture. A high dependence on the presence of acidic compounds and the rate of the reaction was observed, in which trifluoroacetic acid was used to catalyze the reaction between the tested molecules and isoniazid in solution. The differential reactivities of the examined ketones and aldehydes in these condensation reactions demonstrate that the resin can provide selective criteria, preferentially scavenging aldehydes from solution. While benzaldehyde reacted quite quickly with the resin, acetophenone barely had any reaction and remained in solution.

Application of In-Line Mid-Infrared (MIR) Spectroscopy Coupled with Calorimetry for the Determination of the Molar Enthalpy of Reaction between Ammonium Chloride and Sodium Nitrite.

The reaction between ammonium chloride and sodium nitrite has been known for its application as a source of heat because of its large enthalpy of reaction, for which it has been used by the oil industry. There have been no known calorimetric studies for the experimental determination of its molar enthalpy of reaction, which is necessary in order to predict the limits achieved for up-scale applications. Attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) and reaction calorimetry were used to determine this value by using a simple methodology. Both techniques were used concomitantly as a source of information regarding the time-dependent moles converted (Δn) and the amount of exchanged heat (ΔH). The molar enthalpy of reaction was calculated to be -74 ± 4 kcal mol(-1). The percentage between the confidence interval and the calculated value was 5.4%, which shows that the methodology was precise. After the determination of the molar enthalpy of reaction, it was proved that the ATR FT-IR alone was able to be used as a substitute for the reaction calorimetry technique, in which the IR signal is converted to the heat information, presenting as an easier technique for the monitoring of the heat released by this system for future applications.