Process Development Of New Type Of Diesel Fuel Cetane Number Improver

To overcome the shortcomings of the research in oxygen polyether type cetane number improver, such as the low conversion of raw material, difficult separation of product, refined difficulty of subsequent product, high cost of production, a new process route was proposed, which consisted of two main steps. Firstly, formaldehyde solution and methanol were used as raw materials to produce high purity methylal with reactive and extractive distillation in one column. Secondly, high purity methylal, high concentration formaldehyde solution and light gasoline were used as raw materials to produce new type of diesel fuel cetane number improver. The new process route not only could significantly improve the conversion of raw materials but also could reduce the production cost and energy consumption.A continuous pilot production of high purity methylal was carried out with reactive and extractive distillation column. Appropriate operating conditions were obtained after the optimization of process operating parameters. The formaldehyde solution was fed at the upper extraction section, the methanol was fed at the lower part of the reaction section, the mole ratio of methanol to formaldehyde was 2:1, and the reflux ratio was 1.5. Under above operating conditions, the mass fraction of methylal at the top of column was 99.1%, which could meet the requirement of purity.Single factor experiments and orthogonal experiments were carried out to study the influence factors of the new type of diesel fuel cetane number improver. The suitable reaction conditions were obtained. The mass fraction of formaldehyde solution was 60%, the quality ratio of methylal to light gasoline was 13, the mole ratio of methylal to water (provided by formaldehyde solution) was 1.5:1, the reaction temperature was 150℃, reaction time was 4h, and the catalyst was SAPO-34 whose dosage was 5% of total mass of reactants. The products were tested and its cetane number was between 60 and 62. Then the products were added into diesel up to 10%, the cetane number could be improved 4.1 units without affecting other performance of diesel.A continuous pilot production of new type of diesel fuel cetane number improver was carried out with reactive extraction column. The operating conditions were:the temperature of reactive extraction column was 150.7℃, the oil phase at the top of column was composed of 0.51% formaldehyde,0.75% methanol,3.52% methylal, 12.93% light gasoline,82.29% cetane number improver. The aqueous phase at the bottom of column was composed of 0.97% formaldehyde,1.15% methanol,39.72% water,58.16% methylal.Compared to the disadvantages of traditional process, the new process route proposed in this paper made full use of the olefins of gasoline and made the reaction conditions of olefin hydration more moderate. The application of reactive extraction improved the conversion of raw materials, and significantly reduced the refined difficulties and production costs.