Continuous adiabatic industrial benzene nitration with mixed acid at a pilot plant scale

Abstract

A pilot plant for the continuous adiabatic nitration of benzene was constructed, reproducing the industrial operating conditions, in order to identify the reaction regime prevailing in this industrial process. Important process parameters were tested covering a wide range of operating conditions: reaction temperature (80-135• C), benzene to nitric acid molar feed ratio (0.96-1.15) and stirring speed (390-1700 rpm). The residence time and the sulphuric acid strength were fixed at 2 min and 68%, respectively. The data from a large number of experiments show a good agreement with the results of a mathematical model of the reactor.In the range of operating conditions tested, it was shown that the prevailing reaction regime is the intermediate one (0.3 < Ha < 2). The film model used to predict the mononitrobenzene production according to the intermediate regime achieved a good accuracy. The asymptotic solutions for the fast and slow reaction regimes were compared with the full solution model and it was clearly shown that the last led to improved results. Since the film model is a simple approach to describe the mass transfer with simultaneous chemical reaction, the results achieved confirmed the adequacy of this modelling approach.

Different Modeling Approaches for a Heterogeneous Liquid−Liquid Reaction Process

“…Previous experiments performed in this pilot plant were carried out in the intermediate reaction regime, 26 with 0.3 < Ha < 2. To gather more information on this process and, in particular, on the relevance of some operating conditions, new experiments were performed.…”

“…This result was already addressed and enlightened in previous work. 26 Thus, a complete analysis of all the influential operating conditions should be carried out in order to get more insight into this heterogeneous chemical process. werts models are usually used to mechanistically describe the heterogeneous fluid-fluid reactions.…”

Simulation of adiabatic mononitration of aromatic hydrocarbons by weak nitric acid

“…Для полного расходования азотной кислоты процесс проводят в избытке бензола при высокой темпе ратуре (до 120-170 °С). За счет высокой температуры из массы производится отгонка воды и укрепление серной кислоты до концентрации, позволяющей использовать ее для приготовлении нитросмеси [5][6][7][8].…”

Technology audit process of nitro mixture preparing process for benzene and toluene nitration using non concentrated nitric acid

“…«адиабатическое нитрование», когда процесс проводят при достаточно низком модуле при высокой темпера-туре в условиях избытка бензола или толуола [8][9][10][11][12]. Это позволяет значительно повысить производительность стадии нитрования и получать мононитросоединения с минимальным содержанием динитросоединений.…”