CN101503338A - Rapid liquefaction method for corps wastes by microwave heating catalysis - Google Patents

Abstract

The invention provides a method for microwave heating to catalyze the liquefaction of crop waste. The method adopts adding the crop waste into polyalcohol and sulfuric acid, microwave heating, controlling the temperature at 150-180 DEG C, and performing the liquefaction reaction for 10-30 minutes. The invention realizes the rapid liquefaction of crop waste by using microwave-assisted heating and reaction catalytic effect, greatly improves the efficiency and effect of liquefaction of crop waste, and the liquefaction rate reaches over 90%; the method is fast, simple and efficient in operation , greatly reducing the cost of crop waste liquefaction.

Description

A method for rapid liquefaction of crop wastes catalyzed by microwave heating

technical field

The invention relates to a method for utilizing agricultural waste, in particular to a method for preparing biomass polyols which can quickly liquefy agricultural waste and greatly improve the liquefaction effect.

Background technique

With the society's increasing demand for energy, the main energy fossil fuels are rapidly decreasing. Therefore, countries around the world have begun to pay extensive attention to the development and utilization of agricultural and forestry biomass resources to replace traditional energy sources.

my country is a large agricultural country with abundant crop straw resources and large reserves. In 2005, my country's straw output exceeded 668 million tons. With the development of rural economy, the change of energy structure and the reduction of rural resident population and labor force, the straw used as energy for rural life has been significantly reduced, and more and more straw has been burned directly, causing serious environmental pollution. It is urgent to develop new ways and methods of straw utilization to change the contradiction between the current energy shortage and environmental pollution and the idle waste of a large number of straw resources.

Although straw fiber raw materials have relatively ideal physical and chemical properties such as energy storage, renewable, and easy to decompose, it is difficult to directly use them due to their low density, low calorific value, insoluble, and infusible properties; After liquefaction under certain technical conditions, it becomes a highly reactive liquid substance containing a large number of hydroxyl groups, that is, biomass polyols, which can be used to replace traditional chemical raw materials for the synthesis of various polymer materials. In recent years, it has attracted widespread attention. It not only opens up a new way of comprehensive utilization of agricultural and forestry waste, but also helps to alleviate the dependence on petrochemical resources and reduce environmental pollution.

At present, the liquefaction technology of straw biomass mainly adopts oil bath heating (90-200° C.) to catalyze the liquefaction of straw, and the liquefaction time is relatively long, usually 1-2 hours (CN101172932A, CN101186559A, CN101186560A, etc.), using cheap ethylene glycol as The liquefaction yield is only 60-70% when the liquefaction agent is used, and the liquefaction yield can only reach 80-90% if the polyethylene glycol or ethylene carbonate with higher price is used. Therefore, the traditional liquefaction technology has long liquefaction time, low efficiency, Disadvantages such as high cost are not conducive to large-scale application.

Contents of the invention

The purpose of the present invention is to solve the problems of long liquefaction time and low liquefaction rate of agricultural waste by conventional heating, and provide a method for liquefying agricultural waste by microwave heating to catalyze the liquefaction of agricultural waste, so as to realize fast and efficient liquefaction of agricultural waste.

In order to achieve the purpose of the present invention, a method for liquefying agricultural wastes catalyzed by microwave heating of the present invention comprises the steps of: adding agricultural wastes to polyol and sulfuric acid, heating with microwaves, controlling the temperature at 150-180°C, and performing the liquefaction reaction 10 to 30 minutes.

Wherein, the crop waste is corn stalks, wheat straws, rice straws, cotton stalks or corncobs.

The crop waste can be crushed to 20-100 mesh first.

In the present invention, a microwave heating device with airtight temperature control and adjustable power can be selected, and the microwave power is controlled at 400-1000W.

The polyhydric alcohol is a liquefaction agent, adopting ethylene glycol, or a mixture of polyethylene glycol 400 and glycerin at a volume ratio of 4:1.

The added amount of the crop waste accounts for 20-30% of the weight of the polyol.

The sulfuric acid is used as a catalyst, preferably 98% concentrated sulfuric acid, and its addition is 3-5% of the weight of the polyol.

The invention introduces the microwave auxiliary heating technology into the liquefaction of crop waste, and through microwave heating and catalysis, the materials can be heated rapidly and the liquefaction reaction can be catalyzed. After comparing microwave heating with traditional oil bath, it is found that the liquefaction rate of microwave heating is significantly higher than that of traditional oil bath, as shown in Figure 1. Therefore, the present invention can overcome the shortcomings of long liquefaction time and low liquefaction rate in traditional oil bath heating liquefaction, achieve the effect of quickly liquefying agricultural waste in a short time, and the liquefaction rate reaches more than 90%. The method is fast, simple and efficient in operation, and greatly reduces the cost of liquefying agricultural waste.

Description of drawings

Figure 1 is a comparison diagram of the effects of liquefying corn stalks to prepare polyols by microwave heating and oil bath heating respectively.

Detailed ways

The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

Example 1

Crush corn stalks to 40 mesh, weigh 6 g of corn stalk powder, add 20 g of liquefier ethylene glycol and 0.7 g of catalyst 98% concentrated sulfuric acid, that is, the mass of straw is 30% of the mass of liquefier, and the concentrated sulfuric acid is 3.5% of the mass of liquefier , set the microwave temperature at 160°C, the microwave power at 600W, adopt a closed microwave heating method, and magnetically stir the liquefaction reaction for 25 minutes to obtain the corn stalk liquefaction product biomass polyol.

After testing, the liquefaction rate of corn stalks reached 94.6% under the liquefaction conditions.

Example 2

Crush the corn stalks to 40 mesh, add the liquefaction agent polyethylene glycol 400 and glycerin 4:1 (v/v) mixture and the catalyst 98% concentrated sulfuric acid to the corn stalk powder, the mass of the liquefaction agent is 25g, and the mass of the straw is the mass of the liquefaction agent The concentrated sulfuric acid is 3.5% of the mass of the liquefaction agent, the microwave temperature is set at 150°C, the microwave power is 400W, and the closed microwave heating is adopted, and the liquefaction reaction is carried out by magnetic stirring for 20 minutes to obtain the corn stalk liquefaction product biomass polyol.

After testing, the liquefaction rate of corn stalks reached 92.4% under the liquefaction conditions.

Example 3

Corncobs are pulverized to 40 mesh, liquefaction agent ethylene glycol and catalyst 98% concentrated sulfuric acid are added to the corncob powder, the quality of the liquefaction agent is 250g, the quality of the corncobs is 20% of the quality of the liquefaction agent, and the concentrated sulfuric acid is 5.0% of the quality of the liquefaction agent , set the microwave temperature at 150°C, the microwave power at 1000W, adopt closed microwave heating, and magnetically stir the liquefaction reaction for 20 minutes to obtain the corncob liquefaction product biomass polyol. Under this liquefaction condition, the liquefaction rate of corn cob reaches 91.5%.

Example 4

Wheat straw is pulverized to 20 orders, and liquefier ethylene glycol and catalyst 98% concentrated sulfuric acid are added in wheat straw powder, and the quality of liquefaction agent is 25g, and straw quality is 20% of the quality of liquefaction agent, and concentrated sulfuric acid is 3.5% of the quality of liquefaction agent, The microwave temperature was set at 160° C., the microwave power was 600 W, a closed microwave was used for heating, and magnetic stirring was used for liquefaction reaction for 20 minutes to obtain biomass polyol, a liquefaction product of wheat straw. Under this liquefaction condition, the liquefaction rate of corn stalks reaches 92.2%.

Example 5

Corn stalks are crushed to 40 orders, liquefaction agent ethylene glycol and catalyst 98% concentrated sulfuric acid are added to the corn stalk powder, the liquefaction agent quality is 25g, the straw quality is 25% of the liquefaction agent quality, and the concentrated sulfuric acid is 3.0% of the liquefaction agent quality, The microwave temperature was set at 180° C., the microwave power was 600 W, closed microwave heating was used, and the liquefaction reaction was magnetically stirred for 30 minutes to obtain biomass polyols, which were liquefaction products of corn stalks. Under this liquefaction condition, the liquefaction rate of corn stalks reaches 96.5%.

Example 6

Corn stalks are pulverized to 100 mesh, liquefaction agent ethylene glycol and catalyst 98% concentrated sulfuric acid are added to the corn stalk powder, the liquefaction agent quality is 25g, the straw quality is 20% of the liquefaction agent quality, and the concentrated sulfuric acid is 3.0% of the liquefaction agent quality, The microwave temperature was set at 180° C., the microwave power was 600 W, a closed microwave was used for heating, magnetic stirring was used for liquefaction reaction for 10 minutes, and biomass polyol was obtained as a liquefaction product of corn stalks. Under this liquefaction condition, the liquefaction rate of corn stalks reaches 91.2%.

Example 7

Corn stalks are pulverized to 40 orders, liquefier ethylene glycol and catalyst 98% concentrated sulfuric acid are added to the corn stalk powder, the liquefaction agent quality is 25g, the straw quality is 20% of the liquefaction agent quality, and the concentrated sulfuric acid is 3.5% of the liquefaction agent quality, The microwave temperature was set at 180° C., the microwave power was 600 W, a closed microwave was used for heating, and magnetic stirring was used for liquefaction reaction for 20 minutes to obtain biomass polyol, a liquefaction product of corn stalks. Under this liquefaction condition, the liquefaction rate of corn stalks reaches 97.1%.

Test case

Corn stalks are crushed to 40 orders, liquefier ethylene glycol and catalyst 98% concentrated sulfuric acid are added to the corn stalk powder, the liquefaction agent quality is 25g, the straw quality is 30% of the liquefaction agent quality, and the concentrated sulfuric acid is 3.5% of the liquefaction agent quality, Set the microwave temperature at 160°C, the microwave power at 600W, use closed microwave heating, and magnetically stir the liquefaction reaction for 5, 10, 15, 20, 25, and 30 minutes respectively, and the liquefaction rate of corn straw at different microwave heating liquefaction times is shown in Fig.

Corn stalks are crushed to 40 orders, liquefier ethylene glycol and catalyst 98% concentrated sulfuric acid are added to the corn stalk powder, the liquefaction agent quality is 25g, the straw quality is 30% of the liquefaction agent quality, and the concentrated sulfuric acid is 3.5% of the liquefaction agent quality, The temperature of the oil bath was set at 160°C, and the liquefaction reaction was carried out by mechanical stirring for 30, 60, 90, and 120 minutes respectively, and the liquefaction rate of corn straw with different oil bath heating and liquefaction time was obtained as shown in Figure 1.

It can be seen from Figure 1 that microwave heating can liquefy more than 90% of corn stalks within 30 minutes, while the liquefaction rate of oil bath heating for 1 to 2 hours is only about 70%, so microwave heating liquefaction can greatly shorten the liquefaction Time, significantly improve the liquefaction efficiency, is a fast and efficient liquefaction method.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (7)

1. A method for liquefying agricultural waste, characterized in that it comprises the steps of: adding agricultural waste to polyol and sulfuric acid, heating with microwaves, controlling the temperature at 150-180°C, and performing liquefaction for 10-30 minutes. 2. The liquefaction method according to claim 1, characterized in that, the crop waste is corn stalks, wheat straws, rice straws, cotton stalks or corncobs. 3. The liquefaction method according to claim 1 or 2, characterized in that the power of the microwave device for microwave heating is controlled at 400-1000W. 4. The liquefaction method according to claim 3, wherein the polyhydric alcohol is ethylene glycol, or a mixture of polyethylene glycol 400 and glycerol in a volume ratio of 4:1. 5. The liquefaction method according to claim 1, 2 or 4, characterized in that the added amount of the agricultural waste is 20-30% of the weight of the polyol. 6. The liquefaction method according to claim 5, characterized in that, the sulfuric acid is 98% concentrated sulfuric acid, and its addition amount is 3-5% of the weight of the polyol. 7. The liquefaction method according to claim 1, 2 or 4, characterized in that the crop waste is firstly crushed to 20-100 mesh.