The Process Flow Design Of Hydroxylamine Hydrochloride Production With Reactive Distiliation

Hydroxylamine hydrochloride (HA) as an important chemical product is widely used in chemical and pharmaceutical industries. At present, the syntheses routes of hydroxylamine hydrochloride mainly are nitromethane route, acetone oxime method, nitrification of natural gas nitric oxide catalytic reduction. However these processes do have many shortcomings, such as complicated routes, final treatment multifarious, high capital outlay and low product yield. Meanwhile, as enhancement of environmental protection and sustainable development of HA industry, it is urgent to develop new process for HA.Hydrolysis reaction of ketone oxime is feasible way for HA production. This reaction is a fast reaction which can reach reaction equilibrium instantly. But the equilibrium conversion is low and does not influenced by other factors such as temperature. Thus for high conversion, it is necessary to overcome limitation of thermodynamic equilibrium. In this work, reactive distillation route is presented combing process intensification and characteristics of hydrolysis reaction of ketone oxime. In this route, the by-product is removed through distillation for breaking thermodynamic equilibrium and acquiring high conversion, using small molecule ketone oxime as reactant.The influence of pressure on hydrolysis reaction of ketone oxime with reactive distillation is studied. Under normal pressure, reactive temperature is too high and side reaction exists, so product HA is difficult to satisfy industrial requirement. Under reaction temperature of65℃and pressure of20kPa, the yield of HA can be over60%with6mol/L hydrochloric acid reacting with a ratio1:1to ketone oxime. It also finds that tert-butyl alcohol, as one of impurities in ketone oxime feed, doesn’t affect the conversion and selectivity. Pilot test shows that HA with reactive distillation has high quality with purity and impurities meeting the national standards.Based on the results of pilot test and the real condition of plant, a process is worked out for the production of HA with an annual capacity of1000tons. The process includes plants of feed pretreatment and plant of reactive distillation. Material balance and equipments are complied by referring to real condition.Based on the experimental results, mathematic model is established to depict reactive distillation in batch reactor. In this model, boil-up rate is used to depict vapor-liquid mass transfer under reduced pressure. Comparing the evaluation values by reactive distillation model and the experimental results, the prediction values have little deviation with the experimental data. It due to that the boil-up rate in experiment is lower than the rate in ideal for molecular collision.