Dataset from analytical pyrolysis assays for converting waste tires into valuable chemicals in the presence of noble-metal catalysts.

About 25.7 million tons of waste tires (WT) are discarded each year worldwide causing important environmental, and health problems. This waste is difficult to manage and dispose due to its huge rate of generation and its extremely slow biodegradation. Therefore, many efforts are being made to valorise WTs into a series of marketable products under a circular economy framework. In the attempt to convert WT into higher-value products, thermochemical decomposition by pyrolysis has emerged as a promising process [1]. The pyrolysis is a thermochemical transformation (under an oxygen-depleted atmosphere) of the tire´s polymeric constituents: natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR) into three major fractions. These fractions are a gas (10-35%, TPG) which is usually used as a heat source (50 MJ kg-1), a solid consisting mainly of recovered carbon black (12-45%, rCB), and a liquid fraction (35-65%, TPO) containing a complex mixture of organic compounds. Among the high-value compounds that can be found in the TPO are D,L-limonene, isoprene, benzene, toluene, mixed-xylene, ethylbenzene, styrene, p-cymene, and some polycyclic aromatic hydrocarbons. This mixture is commonly used as a diesel substitute and owing to its complex composition it rarely is seen as a source for more valuable products. To overcome such a complexity, and selectively produce specific chemical identities, different types of catalysts have been used [2,3]. Herein, we provide a dataset from a systematic study about catalytic pyrolysis of WT for selectively producing benzene, toluene, and xylenes (BTX) and p-cymene on noble metals (Pd, Pt, Au) supported on titanate nanotubes (NT-Ti). The comprehensive analysis of this data was recently published, thus, the analytical techniques, experimental conditions and dataset are given in the present paper as a complement to that publication [1]. The reaction was evaluated in an analytical pyrolysis unit consisting in a micropyrolizer coupled to a mass spectrometer (Py-GC/MS) operating at temperatures between 400 and 450 °C in a fast pyrolysis regime (12 s). The effectivity of catalysts was measured in terms of selectivity to monoaromatics as BTX and p-cymene, under non-catalytic and for catalytic pyrolysis conditions. Moreover, the reaction was conducted on individual rubbers (Polyisoprene, Polybutadiene, and Styrene-Butadiene) and DL-limonene, to get deep insights into the transformation behaviour and reaction pathways. Therefore, the reader will find a data-in-brief paper containing some characterizations of the WTs used for the investigation, along with a complete dataset of Py-GC/MS results. Finally, the original files for the interpretation of the MS results are also provided, so that the reader can easily use this information to further expand the study to their own interest (industrial or scientific).

Renewable aromatics through catalytic flash pyrolysis of pineapple crown leaves using HZSM-5 synthesized with RHA and diatomite.

The influence of reactor temperature of 300  and 600 °C and the acidity of the ZSM-5 and HZSM-5 catalysts on the pyrolysis product yields of the pineapple crown leaves have been investigated in a fixed bed reactor Py-GC/MS. The ZSM-5 catalyst was hydrothermally synthesized with a Si/Al ratio 50, using residual diatomite and rice husk ash as alternative sources of Al and Si for catalyst cost reduction. For the HZSM-5 synthesis, calcined ZSM-5 was activated by ion exchange between Na+ and H+. The catalysts structure was confirmed by the XRD and Rietveld treatment, SEM, FTIR, FRX, TGA and BET results. Analytical pyrolysis of the biomass was carried out at 500 °C in a Py-5200 HP-R pyrolyzer connected to the GC/MS and the pyrolysis vapors were transported to a catalytic bed at 300 and 600 °C. The results showed that the increase in the catalytic bed temperature promoted increased the aromatic content. The main pyrolysis products of the PCL were oxygenated compounds that were converted at 600 °C using the HZSM-5 catalyst into high value renewable aromatic compounds for the chemical industry, such as benzene, toluene, xylene, etilbenzene, thereby confirming the deoxygenation activity of synthesized catalyst to produce renewable aromatics compounds which are important platform chemicals and precursors for jet fuels, gases, polymers and solvents.

Ex situ catalytic biomass pyrolysis using mesoporous Ti-MCM-41.

Biomass has attracted considerable attention as energy, economic, and environmental asset, as result of its abundance and range of properties. The use of mesoporous catalysts during fast pyrolysis has been a highly important route to improve efficiency as well adding value to biomass. The addition of titanium to molecular sieves increases the efficiency of the pyrolysis reaction by improving production and selectivity of products of interest. This study aims at analyzing the catalytic pyrolysis products of elephant grass using titanium catalysts prepared at different Si/Ti molar ratios, i.e., 25 and 50. The material was supported on MCM-41 for the catalytic pyrolysis of biomass. The biomass pyrolysis reactions were performed in a micropyrolyzer coupled to a GC/MS analyzer. The Ti-MCM-41 samples were characterized by XRD, BET-specific area, and UV-visible. The distribution of pyrolysis products depended on process parameters such as temperature and catalyst type. The highest yield for hydrocarbon production, such as styrene, benzene, methylbenzene, and naphthalene, was observed at 600 °C using Si/Ti equal to 50.