12. Biodiesel

(kindling point) of a substance is the temperature at which it will spontaneously ignite in a normal atmosphere without an external source of ignition ex. flame/spark This temp is required to supply the activation energy needed for combustion.

autoignition temperature

Soap Formation Soap is a fatty acid salt; an undesirable product of FFA reacting with a base catalyst (eg. KOH) exacerbated by presence of water - causing FFA formation water is also a reaction product TO REMOVE FFA: saponification using alkali or esterification using acid catalyst saponification: leads to formation of -soap(triglyceride + KOH/NaOH) binds catalyst in unusable form complicate separation/recovery

How to solve the issues of free fatty acid?

glycerides + Alcohol -> Esters + Glycerin Fat/Oil + Alcohol +Catalyst -> Biodiesel + Glycerol 100 lbs 10 lbs 1 lb 100 lbs 10 lbs

chemistry and mass balance of biodiesel production

refers to the fuel's temperature as it begins to thicken and "cloud"

cloud point

Definition: Can be grown using waste materials such as sewage & without displacing land currently used for food production How select site?/Factors that affect: 1) The water supply/demand, its salinity and chemistry 2)The land topography, geology, and ownership 3)The climate conditions, temperature, insulation, evaporation, precipitation, the easy access to nutrients and carbon energy sources Factors affecting algae growth: 1)abiotic factors such as light (quality, quantity), temperature, nutrient concentration (O2, CO2, pH, salinity, and toxic chemicals) Harvesting Methods: sedimentation, centrifugation, filtration, ultra filtration, sometimes with an additional flocculation step or with a combination of flocculation-flotation able to attain up to 98% quantitative extraction of purified fatty acids with hexane ethanol mixture

Algae as Feedstock

including tallow, lard, yellow grease, chicken fat, and the by-products of the production of omega-3 fatty acids from fish oil

Animals fats as feedstock

Current feedstocks: Plant oils Animal fats Future feedstocks: Algae Lipid producing mircroorganisms

Feedstocks of biodiesel?

"Jatropha" drought-resistant perennial, small evergreen tree 3-4 meters in height can be grown on poorest soils, sandy stony, etc. next to palm oil in energy content 30+ yr harvest life can convert unproductive land to national assets

Microbial Lipids as a feedstock

Reaction time: 20-40 minutes for alkali as catalyst, 3- 18 hour for acid as catalyst Reaction temperature: 50-80 degrees C, rxn rate is proportional to the operating temperature Molar ratio of alcohol to oil: theoretical: 3:1 practice 9-12:1 at least

Representative reaction conditions (temp, time, alcohol to oil) for biodiesel production?

The more unsaturated the fat(more double bonds) the lower the melting point, i.e. iodine value is higher

The effects of lipid (fatty acids) types and chemical structures on biodiesel properties?

-Drugs Medical and pharmaceutical preparations, mainly as a means of improving smoothness, providing lubrication and as a humectant/moisturizer *cough syrups *expectorants *Laxatives *Elixirs Used as a substitute for alcohol, as a solvent that will create a therapeutic herbal extraction -Personal Care Serves as an emollient, humectant/moisturizer, solvent, and lubricant in personal care products *Toothpaste *Mouthwashes *Skin care products *Shaving cream *Hair care products *Soaps -Foods and Beverages *Humectant/moisturizer, solvent and sweetener *Solvent for flavors (such as vanilla) and food colors *Softening agent in candy, cakes *Casings for meats and cheeses *Used in manufacture of poly-glycerol esters going into shortening and margarine *Used as filler in low-fat food products (e.g., cookies) *Used as thickening agent in liqueurs -Polyether Polyols *Polyols for flexible foams, & rigid polyurethane foams *the initiator to which propylene oxide/ethylene oxide is added *Alkyl resins (plastics) and cellophane *Surface coatings and paints *Softener and plasticizer *Casings, collagen casings (medical applications) and non-meat packaging *Plasticizer in cellophane

What are the applications of glycerol?

Catalyst-mixing Transesterification Neutralization Phase Separation Crude Biodiesel Purification Quality Control Methanol Recovery

What are the major operations of base-catalyzed biodiesel production?

refers to alkyl (methyl or ethyl) esters of fatty acids, equivalent to diesel fuel, which can be used (alone, or blended with conventional diesel fuel) in unmodified diesel-engine vehicles

What is biodiesel?

about 1 million gallon a year if entire U.S. supply of vegetable oils and animal fats used to convert to biodiesel, about 7% of US demand would be covered

What is the current production scale of biodiesel in the USA?/How much can biodiesel meet the US diesel market?

unprocessed vegetable oil is NOT biodiesel. Vegetable oil can be used in some diesel engines (especially when heated)

What is the difference between vegetable oil and biodiesel?

% by volume of normal cetane in a mixture of normal cetane & alpha-methyl naphthalene, which has the same ignition characteristics [ignition delay] as the test fuel when combustion is carried out in a standard engine under specified operating conditions. actually a measure of a fuels ignition delay; the time period between the start of injection and start of combustion (ignition) of the fuel. ex. Higher cetane fuels will have short delays and vice-versa

cetane number

lowest temp, expressed in multiples of 1 Degree Celsius; at which a given volume of fuel fails to pass through a standardized filtration device in a specified time when cooled under certain conditions. This test gives an estimate for the lowest temperature that a fuel will give trouble during free flow in certain fuel systems.

cold filter plugging point (CFPP)

of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. At this temp, vapor may cease to burn when the source of ignition is removed.

flashing point

The process by which individual particles of clay aggregate into clotlike masses or precipitate into small lumps occurs as a result of a chemical reaction between the clay particles and another substance, usually salt water.

flocculation

degree of unsaturated/amount of double bonds

iodine value

temperature where biodiesel goes from solid to liquid form

melting point

virgin oil: mostly: rapeseed and soybean oils <-- comes from mustard, flax, sunflower, palm oil, and hemp seed waste vegetable oil (WVO): -from food industry and restaurants (yellow grease)

plant oils feedstock

lowest temperature at which it will pour or flow under prescribed conditions

pour point

and using NaOH to remove Free fatty acids and turns them into soap which increases viscosity and is another way to slow down reaction

what are the effects of free fatty acid on base-catalyzed biodiesel production?

*Defintion: initiates the reaction and allows the fatty acid chains to detach and react with methanol added to form new fatty acid esters *Strong base catalysts typically used: NaOH; KOH; NaOCH3; KOCH3 *Strong acid catalysts may also be used: Sulfuric Acid, phosphoric acid slower process requiring higher temperature requires much higher alcohol to oil ratio better for high FFA feedstocks *enzymatic processes (lipases) alcohol still needed, only replaces catalyst slow, high cost, low yields *heterogenous (solid) catalyst (acid or base) - facilitates catalyst recovery but requires higher temperatures and increased pressures

what catalysts can be used for transesterification reaction for biodiesel production? Their pros and cons?