Evaluation of sodium/protonated titanate nanotubes catalysts in virgin and post consumer PET depolymerization

The high PET consume, mainly as bottles, associated with rapid disposal and high resistance to ambient conditions and biological degradation lead to accumulation in the enviromental, constituting a worrying scenario in world level. Chemical recycle PET by glycolysis is an important alternative, once bis(hydroxiethyl)terephthalate (BHET), high added value monomer, can be obtained. In this context, this study approaches the use of titanate nanotubes (i.e. sodium/protonated titanate nanotubes) as catalyst for PET glycolysis. Reactional conditions, the origin and granulometry of PET flakes were evaluated (at 196 °C). Best results (BHET yield > 80%) were obtained for both catalyst in 3 h of reaction. The protonated titanate nanotubes catalyst were more efficient than sodium titanate nanotubes due to greater concentration of Brönsted and Lewis acid sites, indicated by TPD analyzes

Estudo de nanoestruturas de titanato como catalisadores heterog?neos aplicados na s?ntese de carbonato de glicerol

Submitted by PPG Engenharia e Tecnologia de Materiais ([email protected]) on 2019-06-03T17:01:09Z No. of bitstreams: 1 DISSERTA??O CAROLINA MAJOLO SCHEID.pdf: 2966388 bytes, checksum: 348e4d65d501654c401d9a7607dc221c (MD5)Approved for entry into archive by Sarajane Pan ([email protected]) on 2019-06-17T12:32:20Z (GMT) No. of bitstreams: 1 DISSERTA??O CAROLINA MAJOLO SCHEID.pdf: 2966388 bytes, checksum: 348e4d65d501654c401d9a7607dc221c (MD5)Made available in DSpace on 2019-06-17T12:43:48Z (GMT). No. of bitstreams: 1 DISSERTA??O CAROLINA MAJOLO SCHEID.pdf: 2966388 bytes, checksum: 348e4d65d501654c401d9a7607dc221c (MD5) Previous issue date: 2019-03-27Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPESGlycerol, which comes from 10% of biodiesel production, has been attracting attention in recent times due to its wide applicability in the industry, as for the synthesis of glycerol carbonate (GC). Among the different forms of GC synthesis, an alternative is the glycerol transesterification reaction with dimethyl carbonate (indirect route). However, it is necessary to use catalysts to reach high conversions and selectivity of glycerol carbonate, such as sodium titanate nanotubes (NaTNT) which are shown to be efficient for different reactions (production of biodiesel, another carbonates, among others). Within the context of sustainability, these nanostructures present low cost of production, as well as the opportunity to perform reuse. Thus, the uncalcined and calcined NaTNTs at 300, 500, 600 and 700 ? C were developed in this work in order to produce glycerol carbonate (indirect route). The morphological and structural evaluation of the catalysts revealed the change of nanotubes to nanorods and the transition from anatase to ruthenic phase, when the catalyst was calcined at 700 ? C (NaTNT700). The NaTNT, NaTNT500 and NaTNT700 catalysts show specific surface area values of 155, 88, 19 m?.g-1, respectively, as well as a decrease in pore diameter as the calcination temperature increased and it was not possible to determine for or NaTNT700. The results of catalytic carbonation reaction by indirect route showed high conversions of glycerol (? 99%) and selectivities in GC (? 100%). In addition, the high purity GC was synthesized as shown by ?H-NMR analysis.O glicerol, oriundo de 10% da produ??o de biodiesel, vem chamando aten??o nos ?ltimos tempos devido a sua vasta aplicabilidade na ind?stria como para a s?ntese do carbonato de glicerol (GC). Entre as diversas formas de s?ntese do GC, uma das possibilidades ? a transesterifica??o do glicerol com o carbonato de dimetila (via indireta). Por?m, torna-se necess?ria a utiliza??o de catalisadores para a produ??o de elevadas convers?es e seletividade de carbonato de glicerol, como por exemplo, nanotubos de titanatos s?dicos (NaTNT) que v?m se mostrando eficientes para diferentes rea??es (s?ntese de biodiesel, outros carbonatos, entre outros). Dentro do contexto de sustentabilidade, essas nanoestruturas apresentam baixo custo de produ??o, bem como a oportunidade de reutiliza??o. Dentro desse contexto, os NaTNT n?o calcinados e calcinados em 300, 500, 600 e 700 ?C foram desenvolvidos neste trabalho, com o intuito de produzir o carbonato de glicerol (via indireta). A avalia??o morfol?gica e estrutural dos catalisadores revelou a mudan?a de nanotubos para nanobast?es e a transi??o de fase anatase para rut?lica, quando o catalisador foi calcinado a 700 ?C (NaTNT700). Os catalisadores NaTNT, NaTNT500 e NaTNT700 apresentaram valores de ?rea superficial espec?fica de 155, 88, 19 m?.g-1, respectivamente, bem como uma diminui??o do di?metro de poro a medida em que a temperatura de calcina??o aumentou, n?o sendo poss?vel determinar para o NaTNT700. Os resultados das rea??es catal?ticas de carbonata??o por via indireta apresentaram elevadas convers?es de glicerol (? 99%) e seletividades em GC (? 100%). Al?m disso, o GC com alta pureza foi sintetizado como mostra a an?lise de ?H-RMN