Date of Award

Spring 2018

Document Type

Thesis

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical, Biological and Pharmaceutical Engineering

First Advisor

Edward L. Dreyzin

Second Advisor

Lisa Axe

Third Advisor

Mirko Schoenitz

Abstract

Aromatic compounds such as toluene are commercially nitrated using a combination of nitric acid with other strong acids. This process relies on the use of highly corrosive chemicals and generates environmentally harmful waste, which is difficult to handle and dispose of. In this study aromatic nitration using solvent-free mechanochemical processing of environmentally benign precursors has been achieved and investigated. Mononitrotoluene was synthesized by milling toluene with sodium nitrate and molybdenum trioxide as a catalyst. Several parameters affecting the desired product yield and selectivity were identified and varied. MNT yields in excess of 60% have been achieved in different tests. The desired product yield and selectivity were found to strongly depend on the ratios of the reactants and the catalyst. A parametric study addressed the effects of milling time, temperature, milling media, and catalyst additives on the MNT yield and on the formation of various byproducts. Toluene conversion as a function of milling time exhibited a maximum, which occurred earlier for smaller milling balls. Milling temperature had only a weak effect on MNT formation, but affected the formation of other aromatic byproducts. Replacing various fractions of MoO3 with fumed silica led to an increased yield of MNT for up to 30% of silica. The yield dropped when higher percentages of MoO3 were replaced. The degree of refinement of MoO3 attained in the mill has been quantified by measuring the surface area of the inorganic fraction of the milled material. The surface measurements were correlated with the product yield.

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