Study On Process Of 1, 3-Dichloropropene To 1, 3-Propanediol By Group-Protecting Technology

In this thesis, hydrogenation of 3-chloroallylacetate, which is the key step in the process of 1,3-propanediol from 1,3-dichloropropene by group-protecting technology, is studied.Experiments can be divided into three parts, as follows:In the first part, tentative evaluation experiments were carried out in hydrogenation reactor at atmospheric pressure and 293.15K. Firstly, a series of Pd/C catalysts were prepared by impregnation-reduction method, and effects of activation method of activated carbon, Pd loadings, modifiers and quantity of one of them were investigated. Findings were as follows: carbon activated by phosphoric acid achieved the highest selectivity among all the kinds of carbons; selectivity dropped slightly from the loading of 10%, but stopped at 5%; phosphorous acid elevated selectivity by up to 15%~20%, but activity dropped sharply down to 15%~20% or so; non-polar solvents improved selectivity. Initial conclusion was drawn that hydrodehalogenaion didn't happen to the main product, thus hydrogenation and hydrodehalogenaion were parallel.In the second part, qualitative analysis of the products was carried out by GC-MS, which led to the buildup of the reaction network, it showed that hydrogenolysis of C-O bond took place.apart from that of C-C1 bond. Based on the reaction network, corrected area normalization method using octane as internal standard was adopted in order to give more accurate data. After that, emphasizes were concentrated on the process of the preparation of Pd/y-Al2O3, in which we found that the highest selectivity was achieved under the following conditions:Meanwhile, the reason of low selectivity were further discussed: hydrogenolysis of C-C1 bond might come from the interaction of active sites with vinyl chlorine and allyl chlorine; and that of C-0 bond might result from either strong adsorption of 0 atoms on the active sites or improving effect of resulting HCI.In the Last part, the entire steps of this multiphase catalytic reaction were analyzed, and then internal diffusion and external diffusion were eliminated respectively by improving stirring speed and adopting little particles (r<34um accounted for 93% ), and then a Langmuir-Hinshelwood type kinetic model was evaluated and further simplified.The intrinsic kinetics of catalytic hydrogenation of 3-chloroallylacetate on Pd/gamma-Al2O3 was investigated at temperature from 293.15 K to 313.15 K (l.OMPa) and under pressure from 0.6MPa to 1 .OMPa (303.15K). Based on the experimental data, the parameters in this simplified kinetic model were acquired by data-fitting. The entire intrinsic reaction equations are as follows:the relative errors between the experiment data and calculated ones were below 5 percents. The evolution of selectivity and the effects of reaction temperature and hydrogen pressure were further investigated.