Sustainable Catalysis for Biorefineries

Francesco Frusteri, Donato Aranda, Giuseppe Bonura

• Publisher: Royal Society of Chemistry
• Year: 2018
• eBook ISBN: 9781788014786
• Edition: 1
• Topic: Ciencias físicas
• Subtopic: Ciencia medioambiental

Biorefineries are becoming increasingly important in providing sustainable routes for chemical industry processes. The establishment ofbio-economic models, based on biorefineries for the creation of innovative products with high added value, such as biochemicals and bioplastics, allows the development of "green chemistry" methods in synergy with traditional chemistry. This reduces the heavy dependence on imports and assists the development of economically and environmentally sustainable production processes, that accommodate the huge investments, research and innovation efforts.

This book explores the most effective or promising catalytic processes for the conversion of biobased components into high added value products, as platform chemicals and intermediates. With a focus on heterogeneous catalysis, this book is ideal for researchers working in catalysis and in green chemistry.

CHAPTER 1

Catalysts for Co-processing Biomass in Oil Refining Industry

EDUARDO FALABELLA SOUSA-AGUIAR*^a, VITOR LOUREIRO XIMENES,^b, JOÃO MONNERAT ARAUJO RIBEIRO DE ALMEIDA^a, PEDRO NOTHAFT ROMANO^a AND YURI CARVALHO^a

^a Federal University of Rio de Janeiro (UFRJ), School of Chemistry, Department of Organic Processes, Centro de Tecnologia, Bloco E, Ilha do Fundão, Rio de Janeiro, Brazil;

^b Petrobras Research Centre (CENPES), Cidade Universitária, Ilha do Fundão, Q7, CEP 21949-900, Rio de Janeiro, Brazil
*E-mail: [email protected]

1.1 Introduction

The refining industry has been confronted by challenges whose solution is actually non-trivial. A growing demand for cleaner fuels is generating more stringent environmental regulations all over the world. Additionally, it must be borne in mind that the quality of current crude oil is inferior to that of the crude oil produced several years ago. Indeed, the crude oil nowadays may be rather heavy, acidic and more impure; hence, it will require new steps in the refining process, such as, for instance, desulphurisation units. Such new units, however, are very energy consuming and will certainly reduce the overall thermal efficiency of the refinery, not to mention the profitability thereof. Moreover, conventional desulphurisation processes often require hydrogen, whose production via Shift reaction will also produce CO₂, a well-known greenhouse gas. Thus, society's demand to improve the air quality by using cleaner fuels may come at the expense of higher greenhouse-gas emissions during the production of such fuels. Globalisation and oscillating customer choice, as well as the growing pressure to reduce emissions, are parameters that ought to be taken into account when the overall profitability of the refinery is discussed. Undoubtedly, the aforementioned requirements are changing the traditional goals of petroleum refineries, frequently imposing a riddle whose answer is quite intricate. Clearly, alternative intelligent solutions are not straightforward and must be developed, requiring much effort and research. Nevertheless, the reduction of greenhouse-gas emissions by fostering the deployment of alternative raw materials such as biomass is an option that must not be disregarded. In fact, biomass utilisation is playing an important role in the concept entitled “the refinery of the future”. At any rate, regardless of the new chemical route chosen, the role of catalysis is sovereign, since it is easier to change the catalyst, rather than changing the entire production systems to generate a new drop-in product. New catalysts must be developed, thereby avoiding rather expensive investment in the hardware of the refinery.

As already stated, the refining of the future will deal with the presence of biomass as an alternative feedstock to the traditional oil feedstock. Therefore, it will comprise the concept of Biorefineries, which, according to the 2008 Farm Act,^1–5 may be defined as “a facility (including equipment and processes) that converts renewable biomass into biofuels and bio-based products, and may produce electricity”. More recently, another important concept described by the term Integrated Biorefinery⁶ has been coined. An integrated biorefinery is capable of efficiently converting a broad range of biomass feedstocks into affordable biofuels, biopower, and other bioproducts. By definition, the integrated biorefinery must cope with the problem of residues. Hence, integrated biorefineries are similar to conventional refineries; however, integrated biorefineries still require much research. In other words, new processes must be developed in order to reduce production costs and improve competitiveness. Essentially, the potential of residues must be explored and innovative chemical routes have to be proposed.

The concept of an integrated biorefinery may be applied to several types of traditional refineries, using different raw materials.^7,8 Furthermore, aiming at the better utilisation of existing facilities, co-processing is often indicated. Co-processing is, by definition, the utilisation of blends in already existing units. In principle, vegetable oils can be rather easily co-processed in the installed facilities of refineries. In addition, different types of bio-oils, resulting from both catalytic and non-catalytic pyrolysis of lignocellulosic biomass, can also undergo processing in different units of the refinery.

Vegetable oils are more easily co-processed in existing refinery facilities. Indeed, co-processing of vegetable oils can be incorporated into a refiner’s operating strategy with minimal detriment to catalyst stability or yields; however, the importance of the base feedstock and operational conditions must not be overlooked.

Coconut, sunflower, maize, olive, peanut and cottonseed oils are some of the potential oils proposed for studies in co-processing. Nevertheless, soybean, palm and rapeseed oils, which are readily available, are the most studied vegetable oils.⁹

The basic scheme of vegetable oil processing in refineries encompasses two units: the hydroprocessing unit and the fluid catalytic cracking (FCC) unit. As far as the hydroprocessing unit is concerned, the idea is rather simple. Blend certain amounts of vegetable oils with the regular feedstock of the unit and then allow the operation to proceed as usual. Of course, operational conditions will have to be adjusted to the new feedstock, since a new reaction scheme will take place. As a matter of fact, the following reactions will be carried out:

(a) In the first step of the reaction pathway, the unsaturated fatty acid chains will be rapidly converted into fully saturated n-paraffins;

(b) In the second step, the bonds between fatty acids and glycerol must be broken (cleavage of a carbon–oxygen bond), thereby ensuring that the products will have appropriate size for the diesel pool.

It is obvious that a convenient catalyst should be developed to promote both reactions.

Regarding FCC units, the same philosophy is used, that is to say, the policy of blending. However, unlike hydrotreating units where the catalyst cannot be changed without the unit being shutdown to reload the reactor, continuous replacement of catalyst in the FCC unit permits the refiner to change the inventory and use tailor-made catalyst formulations to optimize yields.

The problems of co-processing bio-oils are often related to the instability thereof. Bio-oils produced via fast pyrolysis present a low-viscosity, single-phase liquid. The deployment of such bio-oils requires that these initial properties be retained. Unfortunately, bio-oils may undergo several reactions, which will provoke an increase in viscosity with time. In fact, bio-oils resulting from fast pyrolysis are not a product of thermodynamic equilibrium, being produced via short contact times and rapid cooling or quenching.

The main reactions that may take place upon storage of bio-oils are the following:⁹

• Organic acids with alcohols to form esters and water;
• Organic acids with olefins to form esters;
• Aldehydes and water to form hydrates;
• Aldehydes and alcohols to form hemiacetals, or acetals and water;
• Aldehydes to form oligomers and resins;
• Aldehydes and phenolics to form resins and water;
• Aldehydes and proteins to form oligomers;
• Organic sulphur to form oligomers;
• Unsaturated compounds to form polyolefins;
• Air oxidation to form more acids and reactive peroxides that catalyze the polymerization of unsaturated compounds.

All those reac...

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• Contents
• Chapter 1 Catalysts for Co-processing Biomass in Oil Refining Industry
• Chapter 2 Catalytic Processes and Catalyst Development in Biorefining
• Chapter 3 Catalysts for Depolymerization of Biomass
• Chapter 4 Advances in Catalytic Processes of Microalgae Conversion into Biofuels and Chemicals
• Chapter 5 Catalysts for Biofuels Production
• Chapter 6 Catalytic Upgrading of Bio-oils
• Chapter 7 Noble Metal Based Bimetallic Catalysts for the Catalytic Hydrotreatment of Phenolic Model Components for (Pyrolytic) Lignins
• Chapter 8 Microwaves in the Catalytic Valorisation of Biomass Derivatives
• Chapter 9 Biohydrogen and Biomethane Production
• Chapter 10 Biochar Production, Activation and Application as a Promising Catalyst
• Subject Index