Abstract
For a long time, many chemical reactions drew on catalysts, products used in smallest quantities compared to products-reagents, to accelerate their kinetics. In certain cases, one of the determining factors to improve these catalysts activities is the use of supports allowing dispersions and thereafter the effectiveness of its active sites.. It is the goal of our study, to increase the pine wood powders value like support of active acid H+ sites of sulphuric acid molecules by hydrogen bond connection with alkenes of aromatics and polynuclear aromatics which were pine wood components and their derivatives obtained after sulphuric acid solution (98%) treatment. Among these derivatives we quote water molecules formed during dehydration and esterification of wood components. Thus, we obtained homogeneous catalysts BXH+, (H+/H2SO4) supported on pine wood powder which we tested by a test reaction: citric acid dehydration to prop-1-ene 1, 2, 3 acid- tricarboxylic acid. Also, the active acid sites (H+/H2SO4) contents and alkenes on BXH+ catalysts were quantified by measuring out respectively with NaOH 0.05N and hydrofluoric acid (HF). This last measuring out enabled us to evaluate the nature of the aromatics and polynuclear aromatics which were the real supports contained in pine wood. At the end, we used these BXH+ synthesized catalysts to catalyze the citric acid black polymer synthesis (PN). The soluble coke and insoluble coke in polar solvent dichloromethane and non-polar solvent hexane of citric acid black polymer synthesized by each catalyst were quantified.
Highlights
The first step of our study consisted in preparing catalysts BXH+, (H+/H2SO4) supported on pine wood powders which were treated with sulphuric acid solution (98%)
We noticed that the BSOHH+ catalyst prepared with methanol-sulphuric acid (98%) solution was initially less active than other catalysts
The non-dried BNSH+ and with methanol BSOHH+ (H+/H2SO4) supported on pine wood powder catalysts whose density were rather important and their calculated specific surface were low had much more activities at 5 minutes (figure 31 (a) and (b)). Those one were still confirmed by the following table 23 which showed the BXH+ catalysts initial activity taking account of each total specific surface. These results confirmed that alkene functions quantities, sulphuric acid quantities were two important parameters for the BXH+ catalyst (H+/H2SO4) supported on pine wood powder, the non-dried BNSH+ and BSOHH+ catalysts with more alkene functions and afterwards able to have good active acid sites by hydrogen bond connections were more active with respectively 53,333.33 [Moles Ac= formed per m2 per moles of H+ and par minute] and 50,000.00 [Moles Ac= formed per m2 per moles of H+ and par minute] initial activities than the dried BSH+ with only 42,000.00 [Moles Ac= formed per m2 per moles of H+ and par minute] initial activity
Summary
The first step of our study consisted in preparing catalysts BXH+, (H+/H2SO4) supported on pine wood powders which were treated with sulphuric acid solution (98%). After sulphuric acid solution (98%) treatment, we obtained two kinds of catalysts: the first was BNSH+ catalysts, (H+/H2SO4) supported on non-dried pine wood powder and the second was BSH+ catalyst, (H+/H2SO4) supported on dried pine wood powder. A part of dried pine wood powders was treated with methanol-sulphuric acid (98%) solution to obtain another type of catalyst: BSOHH+ catalyst, (H+/H2SO4) supported on dried pine wood powder. Andry Tahina Rabeharitsara et al.: Pine Wood Powder Treatment to BXH+ Homogeneous Catalyst (H+/H2SO4) Supported on Its Aromatics’ and PNA’ Alkenes – Application in Black Citric Acid Polymer Synthesis each catalyst test reactions. That led us to the third step, using these catalysts to synthesize citric acid black polymer which their soluble and insoluble coke in dichloromethane and hexane solvents were quantified
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