A biomass fuel and a method for preparing the same

Abstract

The present application relates to the field of fuel technology, disclose a kind of environmental protection type biomass fuel and preparation method thereof.The environmental protection type biomass fuel in the present application includes the following weight parts materials: sawdust 60-70 parts, activated biochar 25-35 parts, phosphoric acid activated red mud 15-20 parts, waste catering oil and fat 3-5 parts, calcium lignosulfonate 2-4 parts, cerium oxide 0.8-1.2 parts;Wherein, the activated biochar is prepared by using rice husk impregnated in ZnCl2 solution;The phosphoric acid activated red mud is prepared by using dried red mud into phosphoric acid solution.This environmental protection type biomass fuel and preparation method thereof provided by the present application improve the combustion characteristics of environmental protection type biomass fuel, improve the combustion efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel technology, in particular to an environmentally friendly biomass fuel and a preparation method thereof. BACKGROUND

[0002] With the increasing depletion of traditional fossil energy and the increasingly serious environmental pollution and climate change problems caused by its burning, finding alternative clean energy has become an important issue in the global energy field. Biomass energy, as a renewable carbon source, has the advantages of abundant reserves, wide distribution, and low pollution, and is considered one of the important directions for future energy structure adjustment. The development and application of environmentally friendly biomass fuel, as an important application form of biomass energy, is of great significance for alleviating energy crisis, reducing greenhouse gas emissions, and protecting the ecological environment.

[0003] Environmentally friendly biomass fuel refers to a solid, liquid or gaseous fuel that is processed and converted from biomass raw materials through physical, chemical or biological methods, has efficient and clean combustion characteristics, and has little environmental impact during production, use and disposal. Biomass raw materials are mainly derived from agricultural waste (such as straw, rice husk), forestry waste (such as branches, bark), urban organic waste and livestock manure, etc. These raw materials can be continuously regenerated through natural growth processes and have the characteristics of sustainable supply. Patent CN118109234A discloses a fuel composition of urban sludge coupled with combustible solid waste, its preparation method and use, which relates to the secondary utilization of solid waste, solves the problem of urban sludge pollution, and reduces the use of coal, saving resources and reducing pollution.

[0004] Biomass absorbs carbon dioxide during growth, and the amount of carbon dioxide released during combustion is basically equal to the amount absorbed during growth, so the combustion of biomass fuel has a carbon neutral effect and can effectively reduce greenhouse gas emissions. At the same time, the content of sulfur, nitrogen and other elements in biomass fuel is relatively low, and the amount of pollutants such as sulfur dioxide and nitrogen oxides produced during combustion is relatively small, causing less environmental pollution. Compared with traditional fossil fuels, some environmentally friendly biomass fuels have lower calorific value, resulting in the need to consume more fuel to meet the same energy demand during combustion. The combustion characteristics of biomass fuel are different from traditional fossil fuels, such as higher ignition temperature and slower combustion speed, which may affect the normal operation of the combustion equipment and the combustion efficiency. Based on this, the present application provides an environmentally friendly biomass fuel and a preparation method thereof. SUMMARY

[0005] The purpose of the present application is to provide an environmentally friendly biomass fuel and a preparation method thereof, which improves the combustion characteristics of the environmentally friendly biomass fuel and improves the combustion efficiency.

[0006] In one aspect, the present application provides an environmentally friendly biomass fuel, comprising the following materials by weight: sawdust 60-70 parts, activated biochar 25-35 parts, phosphoric acid activated red mud 15-20 parts, waste cooking oil 3-5 parts, calcium lignosulfonate 2-4 parts, and cerium oxide 0.8-1.2 parts.

[0007] Further, the preparation method of the phosphoric acid activated red mud comprises: adding the dried red mud into a phosphoric acid solution, stirring at a constant temperature of 75-85°C and a rotation speed of 200-300 rpm for 2-4 h, vacuum filtration, washing the filter cake with deionized water until neutral, and drying in an oven at 100-110°C until the water content is ≤5%.

[0008] Further, the mass concentration of the aqueous phosphoric acid solution is 5-10%, and the usage ratio of the dried red mud to the aqueous phosphoric acid solution is 1:10-12.

[0009] Further, the dried red mud comprises drying the red mud at a temperature of 80-90°C for 4-6 h.

[0010] Further, the preparation method of the activated biochar comprises: immersing the rice husk biochar in a ZnCl2 solution, activating at 110-120°C for 2-4 h, and washing with deionized water until no Cl - , and heating to 550-650°C at a rate of 10°C / min under nitrogen atmosphere, keeping the temperature for 60-70 min, and cooling to room temperature after the reaction is completed.

[0011] Further, the ZnCl2 solution is an aqueous ZnCl2 solution with a mass concentration of 10-12%, and the usage ratio of the rice husk biochar to the ZnCl2 solution is 1 g:4-6 mL.

[0012] Further, the sawdust is wood processing waste, including at least one of pine sawdust, fir sawdust, poplar sawdust, and fruit wood sawdust.

[0013] Further, the waste cooking oil needs to be pretreated, and the steps include: filtering to remove solid impurities, heating to 75-85°C for 1-2 h for dehydration, and then centrifuging at 3000-4000 rpm for 15-20 min to obtain the waste cooking oil.

[0014] Further, the water content of the waste cooking oil is ≤5%, and the acid value is ≤5 mg KOH / g.

[0015] In another aspect, the present application provides a preparation method of an environmentally friendly biomass fuel, comprising the following steps: crushing sawdust into particles with a size of 1-3 mm; weighing raw materials according to a formula, mixing activated biochar, phosphoric acid activated red mud and cerium oxide at a rotating speed of 100-200 r / min for 60-80 min to obtain a catalyst, then placing sawdust, waste catering oil and fat and calcium lignosulfonate in a reactor, stirring at 200-250 rpm for 40-50 min, replacing air with nitrogen, adding the catalyst, heating at a rate of 5 ℃ / min to 380-450 ℃, and performing catalytic cracking under a pressure of 8-12 MPa for 80-100 min; cooling the product after the reaction to 80-100 ℃ for gas-liquid-solid separation, collecting the liquid product; and refining the liquid product to obtain the environmentally friendly biomass fuel.

[0016] The present application has the following advantages:

[0017] The activated biochar and the phosphoric acid activated red mud are modified by physical-chemical synergistic modification in the present application, and a high specific surface area and a multi-level pore structure are constructed. After the activated biochar is impregnated and activated by a ZnCl2 solution, a large number of microporous-mesoporous structures are formed on the surface, which significantly improves the adsorption capacity of volatile organic compounds, and the residual carbon skeleton as a catalytic site can promote the cracking of macromolecular hydrocarbons into small molecule combustible gases. The phosphoric acid activated red mud removes the basic oxides such as CaO and MgO in the red mud by acid leaching treatment, reducing the generation of sulfur oxides in the combustion process; at the same time, the phosphate and the iron and aluminum oxides in the red mud form a phosphate complex, enhancing the thermal stability and catalytic activity of the material. When the two synergistically act, the adsorption-cracking function of the activated biochar and the desulfurization-catalysis function of the phosphoric acid activated red mud form a complement: the former promotes deep cracking by prolonging the residence time of volatile matter, and the latter reduces pollutant emissions by inhibiting sulfur release and catalyzing oxidation reactions, thereby improving the calorific value and combustion efficiency of the fuel.

[0018] In the present application, the waste catering oil is pretreated by dehydration and centrifugation, and the water content is reduced to ≤5%, and the acid value is ≤5 mgKOH / g, effectively inhibiting the side reactions caused by water vapor and the catalyst poisoning caused by free fatty acids in the cracking process. When the pretreated oil and sawdust are co-cracked, the long-chain fatty acid glycerides in the oil are decomposed into short-chain alkanes and olefins at high temperatures, and undergo a synergistic reforming reaction with the cellulose / hemicellulose cracking products in the sawdust, generating more small molecule hydrocarbons with high added value. In addition, the low ash content of the oil reduces the accumulation of inorganic salts in the cracking residue, avoiding the blockage of the catalyst pores, and forming a synergy with the high porosity of the activated biochar, maintaining the sustained and efficient cracking reaction. The oil without pretreatment will cause excessive generation of CO and nitrogen-containing oxides in the cracking gas due to high moisture and high acid value, reducing the fuel quality.

[0019] In the present application, cerium oxide acts as an oxygen storage catalyst, which can store oxygen in the form of Ce3+ / Ce 4+ Redox cycle realizes dynamic regulation of oxygen in combustion process: in oxygen-deficient region, CeO2 releases lattice oxygen to promote deep oxidation of incomplete combustion products such as CO and hydrocarbons; in oxygen-rich region, CeO2 absorbs excess oxygen and inhibits thermal NOx formation caused by local overheating. 3+ CeO2 is oxidized to Ce 4+ and adsorbs excess oxygen, inhibiting thermal NOx formation caused by local overheating. x In addition, the abundant oxygen vacancies on the surface of CeO2 can adsorb SO2 and NO x , and convert them into SO3 and NO2 through catalytic oxidation, which then reacts with basic oxides such as phosphoric acid to generate stable sulfates / nitrates in the MgO in red mud, and are fixed in the ash, significantly reducing the emission of gaseous pollutants. When CeO2 is absent, CO and NO x are emitted in large quantities due to insufficient oxidation, indicating that the oxidation catalytic effect is a key link to achieve clean combustion.

[0020] In the present application, activated biochar, phosphoric acid-activated red mud, and cerium oxide form a ternary catalytic system, which realizes efficient conversion of fuel through a multi-stage reaction path of "adsorption-cracking-oxidation". The microporous structure of activated biochar preferentially adsorbs macromolecular hydrocarbons, and its surface acidic sites such as -COOH and -OH catalyze the cleavage of C-C bonds; Fe2O3 / Al2O3 in phosphoric acid-activated red mud acts as a Lewis acid center to further catalyze the cracking reaction, while its phosphate groups combine with sulfur compounds to form stable salts, inhibiting the release of SO2; CeO2 promotes the complete oxidation of small molecular hydrocarbons through oxygen vacancies, reducing the formation of carbon deposits. When the three components work together, the cracking-desulfurization function of activated biochar and phosphoric acid-activated red mud provides reactants such as CO and uncracked hydrocarbons for the deep oxidation of CeO2, while the oxidation products of CeO2 such as CO2 and H2O reduce the temperature in the cracking zone through dilution effect, inhibiting the formation of tar caused by secondary cracking. Unactivated biochar or untreated red mud will disrupt this synergistic system, leading to insufficient cracking or uncontrolled sulfur release.

[0021] In the present application, the temperature, pressure, and heating rate of catalytic cracking reaction achieve a balance between cracking depth and product selectivity by affecting the diffusion of reactants and the exposure of catalyst active sites. High temperature and high pressure conditions enhance the diffusion rate of volatile matter in the catalyst pores, promoting the adsorption and cracking of macromolecular hydrocarbons; at the same time, slow heating under nitrogen atmosphere avoids local overheating-induced coke deposition, maintaining the sustained activity of the catalyst. If the biochar or red mud is not activated, its low porosity and weak catalytic activity will lead to a decrease in cracking reaction rate and an increase in uncracked components; insufficient pretreatment of oil or the absence of cerium oxide will disrupt the product's calorific value and environmental performance due to increased side reactions or insufficient oxidation. The synergistic optimization of process parameters and component modification is the core guarantee for achieving efficient and clean combustion of fuel. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, but not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] It should be noted that the red mud in the present application is purchased from Shandong Aluminum Industry Co., Ltd. In order to better illustrate the technical solutions of the present application, the sawdust in the embodiments and comparative examples of the present application is poplar processing waste, but it is not limited to poplar processing waste, and also includes at least one of pine sawdust, Chinese fir sawdust, and fruit wood sawdust.

[0024] Example 1

[0025] The present embodiment provides an environmentally friendly biomass fuel, which comprises the following materials by weight: 65 parts of sawdust, 30 parts of activated biochar, 18 parts of phosphoric acid activated red mud, 4 parts of waste catering oil, 3 parts of calcium lignosulfonate, and 1 part of cerium oxide.

[0026] The waste catering oil needs to be pretreated, and the steps include: filtering to remove solid impurities, heating to 80℃ for 1.5h for sedimentation and dehydration, and then centrifuging at 3500rpm for 18min to obtain the waste catering oil; the final water content is 5wt%, and the acid value is 5mg KOH / g.

[0027] The preparation method of the phosphoric acid activated red mud includes: drying the red mud at a temperature of 85℃ for 5h to obtain dried red mud, adding 10g of the dried red mud into 110g of an 8% mass concentration phosphoric acid aqueous solution, stirring at a speed of 250rpm and a temperature of 80℃ for 3h, vacuum filtering, washing the filter cake with deionized water until it is neutral, and drying in an oven at 105℃ until the water content is 5wt%.

[0028] The preparation method of the activated biochar includes: immersing 100g of rice husk biochar in 500mL of an 11% mass concentration ZnCl2 aqueous solution, activating at 115℃ for 3h, washing with deionized water until there is no Cl - , and heating to 600℃ at a rate of 10℃ / min under nitrogen, keeping the temperature for 65min, and cooling to room temperature after the reaction is completed.

[0029] The preparation method of the environment-friendly biomass fuel comprises the following steps: wood chips are crushed into particles with an average particle size of 2 mm, raw materials are weighed according to the formula, activated biochar, phosphoric acid activated red mud and cerium oxide are mixed at a rotating speed of 150 r / min for 70 min to obtain a catalyst, then the wood chip particles, waste cooking oil and calcium lignosulfonate are placed in a reactor and stirred at 220 rpm for 45 min, nitrogen is introduced to replace air, the catalyst is added, the temperature is raised to 410 DEG C at a rate of 5 DEG C / min, and the catalytic cracking reaction is carried out at 10 MPa for 90 min; the product after reaction is cooled to 90 DEG C for gas-liquid-solid separation, and the liquid product is collected; the liquid product is refined, dehydrated to a water content of 0.37% by passing through a 3A molecular sieve column at a temperature of 60 DEG C, and then filtered through a silica gel column with a silica gel:oil ratio of 1:0.2 to remove polar impurities, to obtain the environment-friendly biomass fuel.

[0030] Example 2

[0031] The environment-friendly biomass fuel provided in this embodiment comprises the following materials by weight: wood chips 60 parts, activated biochar 25 parts, phosphoric acid activated red mud 15 parts, waste cooking oil 3 parts, calcium lignosulfonate 2 parts, and cerium oxide 0.8 parts.

[0032] The waste cooking oil needs to be pretreated, and the steps include: filtering to remove solid impurities, heating to 80 DEG C for 1.5 h of dehydration and sedimentation, and then centrifuging at 3500 rpm for 18 min to obtain the waste cooking oil; the final water content is 5wt%, and the acid value is 5mg KOH / g.

[0033] The preparation method of the phosphoric acid activated red mud comprises the following steps: the red mud is dried at a temperature of 80 DEG C for 4 h to obtain dried red mud, 10 g of the dried red mud is added into 100 g of a 5% phosphoric acid aqueous solution, the rotating speed is 200 rpm, the temperature is 75 DEG C, and the stirring is performed for 2 h, vacuum filtration is performed, the filter cake is washed with deionized water until it is neutral, and the filter cake is dried in a 100 DEG C oven until the water content is 5wt%.

[0034] The preparation method of the activated biochar comprises the following steps: 100 g of rice husk biochar is immersed in 400 mL of a 10% ZnCl2 aqueous solution, the temperature is 110 DEG C, and the activation is performed for 2 h, the biochar is washed with deionized water until there is no Cl - , the temperature is raised to 550 DEG C at a rate of 10 DEG C / min under nitrogen, and the temperature is kept for 60 min, and the reaction is completed, and then the temperature is cooled to room temperature.

[0035] The preparation method of the environment-friendly biomass fuel comprises the following steps: wood chips are crushed into particles with an average particle size of 1 mm, raw materials are weighed according to the formula, activated biochar, phosphoric acid activated red mud and cerium oxide are mixed at a rotating speed of 100 / min for 60 min to obtain a catalyst, then the wood chip particles, waste cooking oil and calcium lignosulfonate are placed in a reactor and stirred at 200 rpm for 40 min, nitrogen is introduced to replace air, the catalyst is added, the temperature is raised to 380℃ at a rate of 5℃ / min, and the catalytic cracking reaction is carried out at 8 MPa for 80 min; the product after reaction is cooled to 80℃ for gas-liquid-solid separation, and the liquid product is collected; the liquid product is refined, dehydrated to a water content of 0.31% by passing through a 3Å molecular sieve column at a temperature of 60℃, and then filtered through a silica gel column with a silica gel:oil ratio of 1:0.2 to remove polar impurities, to obtain the environment-friendly biomass fuel.

[0036] Example 3

[0037] The environment-friendly biomass fuel provided in this embodiment comprises the following materials by weight: wood chips 70 parts, activated biochar 35 parts, phosphoric acid activated red mud 20 parts, waste cooking oil 5 parts, calcium lignosulfonate 4 parts, and cerium oxide 1.2 parts.

[0038] The waste cooking oil needs to be pretreated, and the steps include: filtering to remove solid impurities, heating to 80℃ for 1.5h of dehydration and sedimentation, and then centrifuging at 3500 rpm for 18 min to obtain the waste cooking oil; the final water content is 5wt%, and the acid value is 5mg KOH / g.

[0039] The preparation method of the phosphoric acid activated red mud comprises the following steps: the red mud is dried at a temperature of 90℃ for 6h to obtain dried red mud, 10g of the dried red mud is added into 120g of a 10% phosphoric acid aqueous solution, the rotating speed is 300rpm, the temperature is 85℃, and the stirring is carried out for 4h, vacuum filtration is carried out, the filter cake is washed with deionized water until it is neutral, and the filter cake is dried in an oven at 110℃ until the water content is 5wt%.

[0040] The preparation method of the activated biochar comprises the following steps: 100g of rice husk biochar is immersed in 600mL of a 12% ZnCl2 aqueous solution, the temperature is 120℃, and the activation is carried out for 4h, the biochar is washed with deionized water until there is no Cl - , the temperature is raised to 650℃ at a rate of 10℃ / min under nitrogen, and the temperature is kept for 70min, and the reaction is completed, and then the temperature is cooled to room temperature.

[0041] The preparation method of the environment-friendly biomass fuel comprises the following steps: wood chips are crushed into particles with an average particle size of 2 mm, raw materials are weighed according to the formula, activated biochar, phosphoric acid activated red mud and cerium oxide are mixed at a rotating speed of 200 r / min for 80 min to obtain a catalyst, then the wood chip particles, waste cooking oil and calcium lignosulfonate are placed in a reactor and stirred at 250 rpm for 50 min, nitrogen is introduced to replace air, the catalyst is added, the temperature is raised to 450 DEG C at a rate of 5 DEG C / min, and the catalytic cracking reaction is carried out at 12 MPa for 100 min; the product after reaction is cooled to 100 DEG C for gas-liquid-solid separation, and the liquid product is collected; the liquid product is refined, dehydrated to a water content of 0.29% by passing through a 3A molecular sieve column at a temperature of 60 DEG C, and then filtered through a silica gel column with a silica gel:oil ratio of 1:0.2 to remove polar impurities, to obtain the environment-friendly biomass fuel.

[0042] Example 4

[0043] The environment-friendly biomass fuel provided in the embodiment comprises the following materials by weight: wood chips 60 parts, activated biochar 35 parts, phosphoric acid activated red mud 15 parts, waste cooking oil 5 parts, calcium lignosulfonate 2 parts, and cerium oxide 1.2 parts.

[0044] The waste cooking oil needs to be pretreated, and the steps include: removing solid impurities by filtration, heating to 80 DEG C for 1.5 h of dehydration and sedimentation, and then centrifuging at 3500 rpm for 18 min to obtain the waste cooking oil; the final water content is 5wt%, and the acid value is 5mg KOH / g.

[0045] The preparation method of the phosphoric acid activated red mud comprises the following steps: the red mud is dried at a temperature of 80 DEG C for 6 h to obtain dried red mud, 10 g of the dried red mud is added into 100 g of a 10% phosphoric acid aqueous solution, the rotating speed is 200 rpm, the temperature is 85 DEG C, and the stirring is performed for 2 h, vacuum filtration is performed, the filter cake is washed with deionized water until it is neutral, and the filter cake is dried in an oven at 110 DEG C until the water content is 5wt%.

[0046] The preparation method of the activated biochar comprises the following steps: 100 g of rice husk biochar is immersed in 400 mL of a 12% ZnCl2 aqueous solution, and activated at 110 DEG C for 4 h, and then washed with deionized water until there is no Cl - , nitrogen is introduced, the temperature is raised to 550 DEG C at a rate of 10 DEG C / min, and the reaction is performed for 70 min, and then the reaction is cooled to room temperature.

[0047] The preparation method of the environment-friendly biomass fuel comprises the following steps: wood chips are crushed into particles with an average particle size of 1 mm, raw materials are weighed according to a formula, activated biochar, phosphoric acid activated red mud and cerium oxide are mixed at a rotating speed of 100 r / min for 80 min to obtain a catalyst, then the wood chip particles, waste cooking oil and calcium lignosulfonate are placed in a reactor and stirred at 200 rpm for 50 min, nitrogen is introduced to replace air, the catalyst is added, the temperature is increased to 380℃ at a rate of 5℃ / min, and the catalytic cracking reaction is carried out at 12 MPa for 80 min; the product after reaction is cooled to 100℃ for gas-liquid-solid separation, and the liquid product is collected; the liquid product is refined, dehydrated to a water content of 0.35% by passing through a 3Å molecular sieve column at a temperature of 60℃, and then filtered through a silica gel column with a silica gel: oil ratio of 1:0.2 to remove polar impurities, so as to obtain the environment-friendly biomass fuel.

[0048] Comparative Example 1

[0049] Different from Example 1, in the present comparative example, the activated biochar is replaced by an equal amount of original rice husk biochar, which is not impregnated with ZnCl2 and high-temperature treated.

[0050] Comparative Example 2

[0051] Different from Example 1, in the present comparative example, the raw materials do not contain activated biochar.

[0052] Comparative Example 3

[0053] Different from Example 1, in the present comparative example, the phosphoric acid activated red mud is replaced by an equal amount of unactivated red mud.

[0054] Comparative Example 4

[0055] Different from Example 1, in the present comparative example, the raw materials do not contain phosphoric acid activated red mud.

[0056] Comparative Example 5

[0057] Different from Example 1, in the present comparative example, the waste oil is not pretreated, and the original waste cooking oil is used without filtration, dehydration and centrifugation, with an acid value of 20 mg KOH / g and a water content of 15%.

[0058] Comparative Example 6

[0059] Different from Example 1, in the present comparative example, the raw materials do not contain cerium oxide.

[0060] Calorific value: tested according to GB / T 384-1981 standard.

[0061] Combustion efficiency: take 1.0 g of fuel sample of the example / contrast example fuel, place it in a quartz boat, and heat it to 850℃ at a rate of 10℃ / min, start timing when it reaches 850℃ (t=0), record the sample mass (mt) every 30 seconds, when the mass change rate is less than 0.1% / min for 3 consecutive times, it is determined that the combustion is complete, and the time is recorded;

[0062] Pollutant emission test: a smoke analyzer (Testo 350) is used to monitor the CO emission concentration (ppm), NO x emission concentration (ppm), and SO2 emission concentration (ppm) in the combustion tail gas online.

[0063] Table 1 test results

[0064] Group Heat value (MJ / kg) Burnout time (min) CO emission concentration (ppm) SO2emission concentration (ppm) NO x Emission concentration (ppm) Example 1 40.2 17.8 79 30 105 Example 2 39.3 19.5 98 42 125 Example 3 39.8 18.2 85 35 112 Example 4 39.5 20.1 105 48 135 Comparative Example 1 38.3 25.6 185 68 180 Comparative Example 2 37.7 28.3 220 85 205 Comparative Example 3 39.1 23.2 150 210 160 Comparative Example 4 38.5 32.5 255 320 240 Comparative Example 5 36.8 35.7 380 55 285 Comparative Example 6 39.1 19.2 305 38 195

[0065] According to the foregoing, examples 1-4 of the present application improve the porosity and catalytic activity by activating biochar; the phosphoric acid activated red mud effectively desulfurizes and catalytically cracks; the oil and fat pretreatment reduces combustion by-products; and cerium oxide promotes complete oxidation and reduces CO emissions, thereby achieving high calorific value, efficient combustion, and ultra-low emissions.

[0066] In contrast example 1, the calorific value decreased by 4.7%, the burnout time increased by 44%, and the emission concentration increased by 134-126%. The unactivated biochar has low porosity and weak catalytic activity, leading to insufficient cracking and reduced combustion efficiency; in contrast example 2, the calorific value decreased by 6.2%, the burnout time increased by 59%, and the pollutants increased by 179-183%. The loss of the catalytic support of biochar reduces the reaction rate and increases uncracked components; in contrast example 3, SO2 emissions increased by 600%, and NO x increased by 52%. The sulfides in the red mud are not removed by phosphoric acid activation, and a large amount of SO2 is released during combustion; the catalytic activity of unactivated red mud is insufficient, leading to increased conversion of nitrogen oxides; in contrast example 4, SO2 increased by 967%, and the burnout time increased by 83%. The loss of the desulfurization function and cracking catalysis of red mud directly releases sulfides, and the reaction rate is significantly reduced; in contrast example 5, the calorific value decreased by 8.5%, CO increased by 381%, and NOx increased by 171%. The high moisture and acid value lead to an increase in cracking side reactions, generating a large amount of incomplete combustion products (CO) and nitrogen-containing oxides; in contrast example 6, CO increased by 286%, and NO x increased by 86%. The lack of oxidation catalysis of cerium oxide leads to insufficient oxidation of CO; at the same time, the increase in incomplete combustion products increases NO x generation.

[0067] Finally, it should be noted that the above examples are only used to illustrate the present application and are not intended to limit the technical solutions described in the present application; those of ordinary skill in the art should understand that the present application can still be modified or equivalently replaced; and all technical solutions and improvements that do not deviate from the spirit and scope of the present application should be covered in the scope of the claims of the present application.

Claims

1. A biomass fuel, characterized by, The following weight parts of raw materials are used: sawdust 60-70 parts, activated biochar 25-35 parts, phosphoric acid activated red mud 15-20 parts, waste catering oil 3-5 parts, calcium lignosulfonate 2-4 parts, cerium oxide 0.8-1.2 parts; wherein the activated biochar is prepared by impregnating rice husk in a ZnCl2 solution; the phosphoric acid activated red mud is prepared by adding dried red mud into a phosphoric acid aqueous solution; The preparation method of the phosphoric acid activated red mud comprises: adding dried red mud into a phosphoric acid aqueous solution, stirring at a constant temperature of 75-85℃ and a rotation speed of 200-300 rpm for 2-4 h, vacuum suction filtration, washing the filter cake with deionized water until neutral, and drying in an oven at 100-110℃ until the water content is ≤5% to obtain the product; The preparation method of the activated biochar comprises: immersing rice husk biochar in a ZnCl2 solution, activating at 110-120 ℃ for 2-4 h, and washing with deionized water until no Cl - is obtained after cooling to room temperature after the reaction is completed. The preparation method of the biomass fuel is as follows: crushing sawdust into particles of 1-3 mm; weighing the raw materials according to the formula, mixing the activated biochar, phosphoric acid activated red mud and cerium oxide at a rotation speed of 100-200 r / min for 60-80 min to obtain a catalyst, then placing the sawdust, waste catering oil and calcium lignosulfonate in a reactor, stirring at 200-250 rpm for 40-50 min, replacing air with nitrogen, adding the catalyst, heating to 380-450℃ at a rate of 5℃ / min, and performing catalytic pyrolysis under a pressure of 8-12 MPa for 80-100 min; cooling the product to 80-100℃ for gas-liquid-solid separation, collecting the liquid product; and refining the liquid product to obtain the biomass fuel.

2. The biomass fuel according to claim 1, wherein, The mass concentration of the phosphoric acid aqueous solution is 5-10%; the ratio of the amount of the dried red mud to the amount of the phosphoric acid aqueous solution is 1:10-12.

3. The biomass fuel according to claim 1, wherein The dried red mud comprises drying red mud at a temperature of 80-90℃ for 4-6 h.

4. The biomass fuel according to claim 1, wherein The ZnCl2 solution is a ZnCl2 aqueous solution with a mass concentration of 10-12%, and the ratio of the amount of the rice husk biochar to the amount of the ZnCl2 solution is 1 g:4-6 mL.

5. The biomass fuel according to claim 1, wherein The sawdust is wood processing waste, including at least one of pine sawdust, fir sawdust, poplar sawdust and fruit wood sawdust.

6. The biomass fuel according to claim 1, wherein The waste catering oil needs to be pretreated, and the steps include: filtering to remove solid impurities, heating to 75-85℃ for 1-2 h of dehydration and sedimentation, and then centrifuging at 3000-4000 rpm for 15-20 min to obtain the waste catering oil.

7. The biomass fuel according to claim 6, wherein The water content of the waste catering oil is ≤5%, and the acid value is ≤5 mg KOH / g.