"BIODIESEL PRODUCTION PROCESS WITHOUT CATALYST IN

CONTINUOUS CONDITIONS"

Biodiesel is a potential substitute for diesel oil, which consists of an alkyl (methyl or ethyl) mixture, fatty acid esters obtained from the transesterification of vegetable oils with small chain alcohols (methanol or ethanol). Generally, there are two routes for the conduction of the transesterification reaction: a catalytic and a non- catalytic one.

Within the catalytic route, the processes with basic and/or acid (chemical catalysis) catalysis stand out, as well as the processes that employ enzymes (lipases) as catalysts (biocatalysis). The chemical catalysis (homogeneous or heterogeneous) presents a long history of development, and the biodiesel fuel that is currently produced by such methods is available in the markets of some countries such as the USA, Japan, Australia and western European countries. There are two basic hindrances associated to biodiesel produced through chemical catalysis: in catalysis, the process is relatively slow and demands the removal of the catalyst. For the basic catalyst, apart from the purification of the catalyst's product, the removal of byproducts from the saponification reaction is necessary. The process consists of the transesterification reaction, the recovery of non-reactive alcohol, purification of alkyl-esters and catalyst, and the separation of glycerin from the reaction byproducts. Thus, the process in inevitably connected to high production costs, presenting high energetic consume.

Part of the hindrances of homogeneous chemical catalysis (product purification) can be avoided through the use of

heterogeneous catalysts and/or with enzymes as catalysts. Such processes still present high costs for the catalysts (heterogenization of catalysts and enzymes). Furthermore, in such processes, the reactional time is even higher for they constitute reactions with heterogeneous catalysts.

A process was recently presented in the literature which indicates the non-catalytic conduction of the transesterification reaction in supercritical methanol (Saka and Kusdiana, Fuel, 2001 , 80, 225-231 ; Saka and Kusdiana, Fuel, 2001 , 80, 693-693; Kusdiana and Saka, Bioresource Technology, 2004, 91 , 289-295).

The authors presented a batch laboratory process to conduct the reaction. In this process, a determined amount of methanol and canola oil (methanol/oil mass proportion between 3.5:1 up to 42:1) was inserted in an autoclave and submersed in a thermostatized bath with controlled temperature (between 200 and 450oC [sic]). After a determined amount of time, the reactor was removed from the hot bath and inserted in a bath at room temperature so as to decrease its temperature. The reactor was then opened and reaction products analyzed. The results indicated than in a 6-minute time at 350 ⁰ C temperatures and pressures of around 400 Bars, vegetable oil triglycerides and fatty acids can be converted to methyl esters from such oils with conversions near to 100%. The authors compared the results with products obtained from different routes (acid and basic catalysis), and with commercial biodiesel. We can mention the works of Dadan Kusdiana and Shira Sake as state of technique, and the documents US 2004/0.022.929; US 2003/0.032.826; BR 0105888-6; US 6.712.867; WO 03/22961 ; WO

2004/108873; US 6.211.390; US 6.174.501 ; US 6.015.440; US 5.525.126; US 4.695.411 ; BR 0104107-0; BR 8300429-7; BR 8302341-0, and others.

Within this scenario, it is important to highlight that the great majority of processes presented in the literature and in patents are catalytic processes (homogeneous or heterogeneous chemical catalysts, and enzymes); these are processes than employ methanol as solvent and are non-continuous processes (batch).

For the aim of this patent, we present a non-catalytic, continuous process that has lower production costs and does not generate polluting residues.

In order to better understand the process of this patent, it is represented in:

FIG. 01 - schematic representation of the basic process; FIG. 02 - Schematic representation of the alcohol variation cooling the cooler [sic] and returning to the alcohol dose dispenser - vegetable oil;

FIG. 03 - Schematic representation with hot water washing unit;

FIG. 04 - Schematic representation with centrifugation unit. The aim of this patent is about a non-catalytic process to produce biodiesel in a continuous process that employs ethanol or methanol as solvent. The basic process consists of pumping a mixture of alcohol and vegetable oil (13) through a pump (01 ) to a tubular reactor (2) where it will be submitted to high temperature (between 150° and 450°) and pressure (between 20 and 400 Bars), where it undergoes the reactions in the time determined by the length of the reactor and displacement speed of the mixture. When exiting the reactor, the

mixture goes through a valve (03), which together with the pump (01) maintain the correct pressure and vacuum inside the tubular reactor (02) consisting of non-reactive ethanol or methanol glycerin and a mixture of esters (biodiesel). The settlement time of the mixture (reactor's volume divided by the vacuum of the mixture) inside the reactor (between 30 seconds and 180 minutes), is controlled by the pump (01) and/or valve (03). At the valve's exit (03), the mixture is cooled in a cooler (07) and it is then conducted to the exit reservoir of the reactor (08) where three phases are present: an upper phase (04) (mainly alcohol (12) which can be ethanol or methanol), an intermediate phase (05) (greatest part of the esters mixture) forming the biodiesel (10), and a lower phase (06) (greatest glycerin part (11 )).

The alcohol (12) (ethanol or methanol) of the upper phase is separated and redirected to the alcohol return (15) tubing to the pump entry (01) of the tubular reactor (02), or then burnt to heat the tubular reactor (02) up in the burner (14), or to both of them. The biodiesel (10) and glycerin (11) phases are forwarded to the separation reservoir (09) where they will be purified by evaporation, and the surplus alcohol (12) (ethanol or methanol) is forwarded to the return tubing (15). At the end of the process, the biodiesel (10) and the glycerin (11) result.

In order to obtain better output of the basic process, variants that aim at optimizing it were developed.

By using these variants as a base, the cooling of the cooler (07) with cold alcohol (12) can be done by pumping it through an alcohol pump (17), which, after exchanging heat, and being then heated up, returns to the alcohol dose dispenser - vegetable oil (18), which will

dose this mixture in the ideal proportion. This heated alcohol improves the thermal output of the system for it will already enter the tubular reactor (02) heated up.

In another variant and in order to accelerate and improve the separation of residual alcohol from the biodiesel after the decantation in separation reservoir or decantation tank (09), this biodiesel (10) and alcohol (12) mixture passes through a washing unit with hot water (19), where the withdrawn alcohol (12) may then be separated through distillation in the distiller (20) and reused, or entered in the alcohol return tubing (15), or directed to burners (14) in the tubular reactor (02), or to the burners of the distiller (20) itself, or to both. In order to optimize the thermal output of the equipment, the water (23) may be used as cooling liquid in the cooler (07) by pre-heating or heating it, and canalizing the hot water (21 ) through the tubing. In another variant, when we do not have space for separation reservoirs or decantation tank (09), or when we want to accelerate the processing without having to wait the necessary time for the separation by decantation, we can use one or more centrifugation units (22) for the alcohol mixture - biodiesel (10) (12) and glycerin (11), or only for the alcohol mixture - biodiesel (10) (12), giving glycerin directly out, resulting in separated alcohol (12), biodiesel (10) and glycerin (11 ) exits.

The description of the process and its variants were performed separately, but the process may encompass the combination of the variants so as to obtain greater process efficiency.